From f8898c86c44be2b0c1f75bcf7fe6ce492ed40f03 Mon Sep 17 00:00:00 2001
From: Dobrunia Kostrigin <48620984+Dobrunia@users.noreply.github.com>
Date: Wed, 11 Feb 2026 19:07:27 +0300
Subject: [PATCH 1/7] Fix beforeSend and beforeBreadcrumb hooks to preserve
 original payload on invalid return

---
 package.json               |  2 +-
 src/index.ts               | 30 ++++--------
 src/modules/breadcrumbs.ts | 20 ++++----
 tests/before-send.test.ts  | 94 +++++++++++---------------------------
 tests/breadcrumbs.test.ts  | 66 +++++++++++++-------------
 5 files changed, 80 insertions(+), 132 deletions(-)

diff --git a/package.json b/package.json
index 28daa85..7ac8307 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@hawk.so/nodejs",
-  "version": "3.3.1",
+  "version": "3.3.2",
   "description": "Node.js catcher for Hawk",
   "license": "AGPL-3.0-only",
   "engines": {
diff --git a/src/index.ts b/src/index.ts
index 5812d88..863eb56 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -294,39 +294,27 @@ class Catcher {
      * Filter sensitive data
      */
     if (typeof this.beforeSend === 'function') {
+      const original = structuredClone(payload);
       const result = this.beforeSend(payload);
 
       /**
-       * Allow user to intentionally drop event by returning false
+       * false → drop event
        */
       if (result === false) {
         return;
       }
 
       /**
-       * If user returned nothing (void/undefined/null) — warn and keep original payload
+       * Valid event payload → use it
        */
-      if (result === undefined || result === null) {
-        console.warn(`[Hawk] Invalid beforeSend value: (${String(result)}). It should return event or false. Event is sent without changes.`);
-      } else if (isValidEventPayload(result)) {
+      if (isValidEventPayload(result)) {
         payload = result;
       } else {
-        let received: string;
-
-        try {
-          received = JSON.stringify(result);
-        } catch {
-          try {
-            received = String(result);
-          } catch {
-            received = Object.prototype.toString.call(result);
-          }
-        }
-
-        console.warn(
-          '[Hawk] beforeSend produced invalid payload (missing required fields), sending original. '
-          + `Received: ${received}`
-        );
+        /**
+         * Anything else is invalid — warn and send original
+         */
+        console.warn('[Hawk] Invalid beforeSend value. It should return event or false. Event is sent without changes.');
+        payload = original;
       }
     }
 
diff --git a/src/modules/breadcrumbs.ts b/src/modules/breadcrumbs.ts
index 9425a36..04937fa 100644
--- a/src/modules/breadcrumbs.ts
+++ b/src/modules/breadcrumbs.ts
@@ -66,6 +66,10 @@ function isValidBreadcrumb(v: unknown): v is Breadcrumb {
 
   const candidate = v as Record<string, unknown>;
 
+  if (typeof candidate.message !== 'string' || (candidate.message as string).trim() === '') {
+    return false;
+  }
+
   if (candidate.timestamp !== undefined && typeof candidate.timestamp !== 'number') {
     return false;
   }
@@ -133,6 +137,7 @@ export class BreadcrumbManager {
     };
 
     if (this.options.beforeBreadcrumb) {
+      const original = structuredClone(bc);
       const result = this.options.beforeBreadcrumb(bc, hint);
 
       /**
@@ -143,17 +148,16 @@ export class BreadcrumbManager {
       }
 
       /**
-       * void/undefined/null — warn and keep original breadcrumb
+       * Valid breadcrumb → use it
        */
-      if (result === undefined || result === null) {
-        console.warn('[Hawk] beforeBreadcrumb returned nothing, storing original breadcrumb.');
-      } else if (isValidBreadcrumb(result)) {
+      if (isValidBreadcrumb(result)) {
         Object.assign(bc, result);
       } else {
-        console.warn(
-          '[Hawk] beforeBreadcrumb produced invalid breadcrumb (must be an object with numeric timestamp), storing original. '
-          + `Received: ${Object.prototype.toString.call(result)}`
-        );
+        /**
+         * Anything else is invalid — warn and restore original
+         */
+        console.warn('[Hawk] Invalid beforeBreadcrumb value. It should return breadcrumb or false. Breadcrumb is stored without changes.');
+        Object.assign(bc, original);
       }
     }
 
diff --git a/tests/before-send.test.ts b/tests/before-send.test.ts
index 4b7f67f..cacfdb9 100644
--- a/tests/before-send.test.ts
+++ b/tests/before-send.test.ts
@@ -94,110 +94,70 @@ describe('beforeSend processing', () => {
     expect(axios.post).not.toHaveBeenCalled();
   });
 
-  it('sends original payload and warns when beforeSend returns undefined (no return)', () => {
-    initWithBeforeSend(() => {
-      /* no return */
-    });
-
-    HawkCatcher.send(new Error('test-undefined'));
-
-    expect(axios.post).toHaveBeenCalledOnce();
-    expect(warnSpy).toHaveBeenCalledOnce();
-    expect(warnSpy).toHaveBeenCalledWith(
-      '[Hawk] Invalid beforeSend value: (undefined). It should return event or false. Event is sent without changes.'
-    );
-
-    const payload = getSentPayload();
-
-    expect(payload.title).toBe('Error: test-undefined');
-    expect(payload.backtrace).toBeInstanceOf(Array);
-  });
-
-  it('sends original payload and warns when beforeSend returns null', () => {
+  it.each([
+    { label: 'undefined', value: undefined },
+    { label: 'null', value: null },
+    { label: 'number (42)', value: 42 },
+    { label: 'string ("oops")', value: 'oops' },
+    { label: 'true', value: true },
+    { label: 'empty object', value: {} },
+  ])('sends original payload and warns when beforeSend returns $label', ({ value }) => {
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    initWithBeforeSend((() => null) as any);
+    initWithBeforeSend(() => value as any);
 
-    HawkCatcher.send(new Error('test-null'));
+    HawkCatcher.send(new Error('test-invalid'));
 
     expect(axios.post).toHaveBeenCalledOnce();
-    expect(warnSpy).toHaveBeenCalledOnce();
     expect(warnSpy).toHaveBeenCalledWith(
-      '[Hawk] Invalid beforeSend value: (null). It should return event or false. Event is sent without changes.'
+      '[Hawk] Invalid beforeSend value. It should return event or false. Event is sent without changes.'
     );
 
     const payload = getSentPayload();
 
-    expect(payload.title).toBe('Error: test-null');
-    expect(payload.backtrace).toBeInstanceOf(Array);
-  });
-
-  it('sends original payload and warns when beforeSend returns invalid value', () => {
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    initWithBeforeSend((() => true) as any);
-
-    HawkCatcher.send(new Error('test-invalid'));
-
-    expect(axios.post).toHaveBeenCalledOnce();
-    expect(warnSpy).toHaveBeenCalledOnce();
-
-    const payload = getSentPayload();
-
     expect(payload.title).toBe('Error: test-invalid');
     expect(payload.backtrace).toBeInstanceOf(Array);
   });
 
-  it('sends original payload and warns when beforeSend returns empty object', () => {
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    initWithBeforeSend((() => ({})) as any);
-
-    HawkCatcher.send(new Error('test-empty-obj'));
-
-    expect(axios.post).toHaveBeenCalledOnce();
-    expect(warnSpy).toHaveBeenCalledOnce();
-
-    const payload = getSentPayload();
-
-    expect(payload.title).toBe('Error: test-empty-obj');
-    expect(payload.backtrace).toBeInstanceOf(Array);
-  });
-
-  it('warns when beforeSend mutates payload to invalid state', () => {
+  it('sends original payload and warns when beforeSend mutates title to empty string', () => {
     initWithBeforeSend((event) => {
       event.title = '';
+
+      return event;
     });
 
     HawkCatcher.send(new Error('test-mutated'));
 
-    expect(warnSpy).toHaveBeenCalledOnce();
     expect(axios.post).toHaveBeenCalledOnce();
+    expect(warnSpy).toHaveBeenCalledWith(
+      '[Hawk] Invalid beforeSend value. It should return event or false. Event is sent without changes.'
+    );
 
+    // structuredClone restores original payload
     const payload = getSentPayload();
 
-    /**
-     * payload was mutated in-place (title = ''), so the sent object has the corrupted title.
-     * The warn is the signal — we verify it fired above.
-     * We still check that backtrace survived to confirm the rest of the payload is intact.
-     */
+    expect(payload.title).toBe('Error: test-mutated');
     expect(payload.backtrace).toBeInstanceOf(Array);
   });
 
-  it('sends event as is and warns when beforeSend deletes required field', () => {
+  it('sends original payload and warns when beforeSend deletes required field (title)', () => {
     initWithBeforeSend((event) => {
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
       delete (event as any).title;
+
+      return event;
     });
 
     HawkCatcher.send(new Error('test-deleted'));
 
-    expect(warnSpy).toHaveBeenCalledOnce();
     expect(axios.post).toHaveBeenCalledOnce();
+    expect(warnSpy).toHaveBeenCalledWith(
+      '[Hawk] Invalid beforeSend value. It should return event or false. Event is sent without changes.'
+    );
 
+    // structuredClone restores original payload
     const payload = getSentPayload();
 
-    /**
-     * title was deleted in-place, so it's undefined on the sent object.
-     * The warn signals the problem. We verify the rest of the payload is intact.
-     */
+    expect(payload.title).toBe('Error: test-deleted');
     expect(payload.backtrace).toBeInstanceOf(Array);
   });
 
diff --git a/tests/breadcrumbs.test.ts b/tests/breadcrumbs.test.ts
index 8be42c5..d486f76 100644
--- a/tests/breadcrumbs.test.ts
+++ b/tests/breadcrumbs.test.ts
@@ -124,25 +124,6 @@ describe('BreadcrumbManager', () => {
       expect(manager.getBreadcrumbs()).toHaveLength(0);
     });
 
-    it('stores original breadcrumb and warns when hook returns null', () => {
-      const manager = BreadcrumbManager.getInstance();
-      const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
-
-      manager.init({
-        // eslint-disable-next-line @typescript-eslint/no-explicit-any
-        beforeBreadcrumb: () => null as any,
-      });
-
-      manager.addBreadcrumb({ type: 'debug', message: 'kept', level: 'info' });
-
-      const crumbs = manager.getBreadcrumbs();
-
-      expect(crumbs).toHaveLength(1);
-      expect(crumbs[0].message).toBe('kept');
-      expect(warnSpy).toHaveBeenCalledWith('[Hawk] beforeBreadcrumb returned nothing, storing original breadcrumb.');
-      warnSpy.mockRestore();
-    });
-
     it('allows modifying breadcrumb in hook', () => {
       const manager = BreadcrumbManager.getInstance();
 
@@ -159,13 +140,19 @@ describe('BreadcrumbManager', () => {
       expect(manager.getBreadcrumbs()[0].message).toBe('modified');
     });
 
-    it('stores original breadcrumb and warns when hook returns undefined (no return)', () => {
+    it.each([
+      { label: 'undefined', value: undefined },
+      { label: 'null', value: null },
+      { label: 'number (42)', value: 42 },
+      { label: 'string ("oops")', value: 'oops' },
+      { label: 'true', value: true },
+    ])('stores original breadcrumb and warns when hook returns $label', ({ value }) => {
       const manager = BreadcrumbManager.getInstance();
       const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
 
       manager.init({
         // eslint-disable-next-line @typescript-eslint/no-explicit-any
-        beforeBreadcrumb: () => undefined as any,
+        beforeBreadcrumb: () => value as any,
       });
 
       manager.addBreadcrumb({ type: 'debug', message: 'kept', level: 'info' });
@@ -174,47 +161,56 @@ describe('BreadcrumbManager', () => {
 
       expect(crumbs).toHaveLength(1);
       expect(crumbs[0].message).toBe('kept');
-      expect(crumbs[0].timestamp).toBeTypeOf('number');
-      expect(warnSpy).toHaveBeenCalledWith('[Hawk] beforeBreadcrumb returned nothing, storing original breadcrumb.');
+      expect(warnSpy).toHaveBeenCalledWith(
+        '[Hawk] Invalid beforeBreadcrumb value. It should return breadcrumb or false. Breadcrumb is stored without changes.'
+      );
       warnSpy.mockRestore();
     });
 
-    it('stores original breadcrumb and warns when hook returns true (invalid)', () => {
+    it('stores original breadcrumb and warns when hook returns object with non-numeric timestamp', () => {
       const manager = BreadcrumbManager.getInstance();
       const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
 
       manager.init({
         // eslint-disable-next-line @typescript-eslint/no-explicit-any
-        beforeBreadcrumb: () => true as any,
+        beforeBreadcrumb: () => ({ timestamp: 'not-a-number', message: 'bad' }) as any,
       });
 
-      manager.addBreadcrumb({ type: 'debug', message: 'kept', level: 'info' });
+      manager.addBreadcrumb({ type: 'debug', message: 'original', level: 'info' });
 
       const crumbs = manager.getBreadcrumbs();
 
       expect(crumbs).toHaveLength(1);
-      expect(crumbs[0].message).toBe('kept');
-      expect(warnSpy).toHaveBeenCalledOnce();
+      expect(crumbs[0].message).toBe('original');
+      expect(crumbs[0].timestamp).toBeTypeOf('number');
+      expect(warnSpy).toHaveBeenCalledWith(
+        '[Hawk] Invalid beforeBreadcrumb value. It should return breadcrumb or false. Breadcrumb is stored without changes.'
+      );
       warnSpy.mockRestore();
     });
 
-    it('stores original breadcrumb and warns when hook returns object with non-numeric timestamp', () => {
+    it('stores original breadcrumb and warns when hook deletes required field (message)', () => {
       const manager = BreadcrumbManager.getInstance();
       const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
 
       manager.init({
-        // eslint-disable-next-line @typescript-eslint/no-explicit-any
-        beforeBreadcrumb: () => ({ timestamp: 'not-a-number', message: 'bad' }) as any,
+        beforeBreadcrumb: (bc) => {
+          // eslint-disable-next-line @typescript-eslint/no-explicit-any
+          delete (bc as any).message;
+
+          return bc;
+        },
       });
 
-      manager.addBreadcrumb({ type: 'debug', message: 'original', level: 'info' });
+      manager.addBreadcrumb({ type: 'debug', message: 'keep-me', level: 'info' });
 
       const crumbs = manager.getBreadcrumbs();
 
       expect(crumbs).toHaveLength(1);
-      expect(crumbs[0].message).toBe('original');
-      expect(crumbs[0].timestamp).toBeTypeOf('number');
-      expect(warnSpy).toHaveBeenCalledOnce();
+      expect(crumbs[0].message).toBe('keep-me');
+      expect(warnSpy).toHaveBeenCalledWith(
+        '[Hawk] Invalid beforeBreadcrumb value. It should return breadcrumb or false. Breadcrumb is stored without changes.'
+      );
       warnSpy.mockRestore();
     });
 

From 7e074256403adf84ecb217e56f5443a69ccef76b Mon Sep 17 00:00:00 2001
From: Dobrunia Kostrigin <48620984+Dobrunia@users.noreply.github.com>
Date: Wed, 11 Feb 2026 19:27:47 +0300
Subject: [PATCH 2/7] Refactor beforeSend and beforeBreadcrumb hooks to use
 cloned payloads for validation, ensuring original data remains intact on
 invalid returns.

---
 src/index.ts               | 15 +++++++--------
 src/modules/breadcrumbs.ts | 15 +++++++--------
 2 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/src/index.ts b/src/index.ts
index 863eb56..35f281b 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -294,27 +294,26 @@ class Catcher {
      * Filter sensitive data
      */
     if (typeof this.beforeSend === 'function') {
-      const original = structuredClone(payload);
-      const result = this.beforeSend(payload);
+      const eventClone = structuredClone(payload);
+      const modified = this.beforeSend(eventClone);
 
       /**
        * false → drop event
        */
-      if (result === false) {
+      if (modified === false) {
         return;
       }
 
       /**
-       * Valid event payload → use it
+       * Valid event payload → use it instead of original
        */
-      if (isValidEventPayload(result)) {
-        payload = result;
+      if (isValidEventPayload(modified)) {
+        payload = modified;
       } else {
         /**
-         * Anything else is invalid — warn and send original
+         * Anything else is invalid — warn, payload stays untouched (hook only received a clone)
          */
         console.warn('[Hawk] Invalid beforeSend value. It should return event or false. Event is sent without changes.');
-        payload = original;
       }
     }
 
diff --git a/src/modules/breadcrumbs.ts b/src/modules/breadcrumbs.ts
index 04937fa..6c48858 100644
--- a/src/modules/breadcrumbs.ts
+++ b/src/modules/breadcrumbs.ts
@@ -137,27 +137,26 @@ export class BreadcrumbManager {
     };
 
     if (this.options.beforeBreadcrumb) {
-      const original = structuredClone(bc);
-      const result = this.options.beforeBreadcrumb(bc, hint);
+      const breadcrumbClone = structuredClone(bc);
+      const modified = this.options.beforeBreadcrumb(breadcrumbClone, hint);
 
       /**
        * false means discard
        */
-      if (result === false) {
+      if (modified === false) {
         return;
       }
 
       /**
-       * Valid breadcrumb → use it
+       * Valid breadcrumb → apply changes from hook
        */
-      if (isValidBreadcrumb(result)) {
-        Object.assign(bc, result);
+      if (isValidBreadcrumb(modified)) {
+        Object.assign(bc, modified);
       } else {
         /**
-         * Anything else is invalid — warn and restore original
+         * Anything else is invalid — warn, bc stays untouched (hook only received a clone)
          */
         console.warn('[Hawk] Invalid beforeBreadcrumb value. It should return breadcrumb or false. Breadcrumb is stored without changes.');
-        Object.assign(bc, original);
       }
     }
 

From 2c0111a3e5c9ccdeb4a288eca74beed742761c8b Mon Sep 17 00:00:00 2001
From: Dobrunia Kostrigin <48620984+Dobrunia@users.noreply.github.com>
Date: Wed, 11 Feb 2026 19:32:29 +0300
Subject: [PATCH 3/7] fix: lint

---
 src/index.ts               |  8 ++++----
 src/modules/breadcrumbs.ts | 10 +++++-----
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/index.ts b/src/index.ts
index 35f281b..fbe84a8 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -295,20 +295,20 @@ class Catcher {
      */
     if (typeof this.beforeSend === 'function') {
       const eventClone = structuredClone(payload);
-      const modified = this.beforeSend(eventClone);
+      const result = this.beforeSend(eventClone);
 
       /**
        * false → drop event
        */
-      if (modified === false) {
+      if (result === false) {
         return;
       }
 
       /**
        * Valid event payload → use it instead of original
        */
-      if (isValidEventPayload(modified)) {
-        payload = modified;
+      if (isValidEventPayload(result)) {
+        payload = result;
       } else {
         /**
          * Anything else is invalid — warn, payload stays untouched (hook only received a clone)
diff --git a/src/modules/breadcrumbs.ts b/src/modules/breadcrumbs.ts
index 6c48858..699a32f 100644
--- a/src/modules/breadcrumbs.ts
+++ b/src/modules/breadcrumbs.ts
@@ -66,7 +66,7 @@ function isValidBreadcrumb(v: unknown): v is Breadcrumb {
 
   const candidate = v as Record<string, unknown>;
 
-  if (typeof candidate.message !== 'string' || (candidate.message as string).trim() === '') {
+  if (typeof candidate.message !== 'string' || candidate.message.trim() === '') {
     return false;
   }
 
@@ -138,20 +138,20 @@ export class BreadcrumbManager {
 
     if (this.options.beforeBreadcrumb) {
       const breadcrumbClone = structuredClone(bc);
-      const modified = this.options.beforeBreadcrumb(breadcrumbClone, hint);
+      const result = this.options.beforeBreadcrumb(breadcrumbClone, hint);
 
       /**
        * false means discard
        */
-      if (modified === false) {
+      if (result === false) {
         return;
       }
 
       /**
        * Valid breadcrumb → apply changes from hook
        */
-      if (isValidBreadcrumb(modified)) {
-        Object.assign(bc, modified);
+      if (isValidBreadcrumb(result)) {
+        Object.assign(bc, result);
       } else {
         /**
          * Anything else is invalid — warn, bc stays untouched (hook only received a clone)

From 567114ab7ca31acf7e7538f09abe2e91a17c491f Mon Sep 17 00:00:00 2001
From: Dobrunia Kostrigin <48620984+Dobrunia@users.noreply.github.com>
Date: Wed, 11 Feb 2026 19:40:17 +0300
Subject: [PATCH 4/7] refactor: rename variable for clarity in beforeSend hook

---
 src/index.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/index.ts b/src/index.ts
index fbe84a8..a3e998b 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -294,8 +294,8 @@ class Catcher {
      * Filter sensitive data
      */
     if (typeof this.beforeSend === 'function') {
-      const eventClone = structuredClone(payload);
-      const result = this.beforeSend(eventClone);
+      const eventPayloadClone = structuredClone(payload);
+      const result = this.beforeSend(eventPayloadClone);
 
       /**
        * false → drop event

From 161b3d54ec46eee536a087a2c4a6e721bf061f1a Mon Sep 17 00:00:00 2001
From: Dobrunia Kostrigin <48620984+Dobrunia@users.noreply.github.com>
Date: Wed, 11 Feb 2026 20:12:02 +0300
Subject: [PATCH 5/7] refactor: update documentation for beforeSend and
 beforeBreadcrumb hooks to clarify return value handling

---
 README.md                  |  3 +--
 src/index.ts               | 15 +++++++++++++--
 src/modules/breadcrumbs.ts | 17 ++++++++++++++---
 types/index.ts             |  2 +-
 4 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/README.md b/README.md
index 8267ce1..9dd1066 100644
--- a/README.md
+++ b/README.md
@@ -240,8 +240,7 @@ Use the `beforeSend()` hook to filter data before sending to Hawk.
 
 - **Return modified event** — the modified event will be sent
 - **Return `false`** — the event will be dropped entirely
-- **Return nothing (`void` / `undefined` / `null`)** — the original event will be sent as-is
-- If `beforeSend` returns an invalid payload, a warning is logged and the original event is sent
+- **Any other value is invalid** — the original event is sent as-is (a warning is logged)
 
 ```js
 HawkCatcher.init({
diff --git a/src/index.ts b/src/index.ts
index a3e998b..5fce8f4 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -70,7 +70,7 @@ class Catcher {
    *
    * - Return modified event — it will be sent instead of the original.
    * - Return `false` — the event will be dropped entirely.
-   * - Return nothing (`void` / `undefined` / `null`) — the original event is sent as-is (a warning is logged).
+   * - Any other value is invalid — the original event is sent as-is (a warning is logged).
    */
   private readonly beforeSend?: (event: EventData<NodeJSAddons>) => EventData<NodeJSAddons> | false | void;
 
@@ -294,7 +294,18 @@ class Catcher {
      * Filter sensitive data
      */
     if (typeof this.beforeSend === 'function') {
-      const eventPayloadClone = structuredClone(payload);
+      let eventPayloadClone: EventData<NodeJSAddons>;
+
+      try {
+        eventPayloadClone = structuredClone(payload);
+      } catch {
+        /**
+         * structuredClone may fail on non-cloneable values (functions, class instances, etc.)
+         * Fall back to passing the original — hook may mutate it, but at least reporting won't crash
+         */
+        eventPayloadClone = payload;
+      }
+
       const result = this.beforeSend(eventPayloadClone);
 
       /**
diff --git a/src/modules/breadcrumbs.ts b/src/modules/breadcrumbs.ts
index 699a32f..ccd7ce2 100644
--- a/src/modules/breadcrumbs.ts
+++ b/src/modules/breadcrumbs.ts
@@ -29,8 +29,8 @@ export interface BreadcrumbsOptions {
    * Hook called before each breadcrumb is stored.
    * - Return modified breadcrumb — it will be stored instead of the original.
    * - Return `false` — the breadcrumb will be discarded.
-   * - Return nothing (`void` / `undefined` / `null`) — the original breadcrumb is stored as-is (a warning is logged).
-   * - If the hook returns an invalid value, a warning is logged and the original breadcrumb is stored.
+   * - Any other value is invalid — the original breadcrumb is stored as-is (a warning is logged).
+   *
    * @param breadcrumb - Breadcrumb to store (can be mutated and returned)
    * @param hint - Optional context (e.g. for filtering)
    */
@@ -137,7 +137,18 @@ export class BreadcrumbManager {
     };
 
     if (this.options.beforeBreadcrumb) {
-      const breadcrumbClone = structuredClone(bc);
+      let breadcrumbClone: Breadcrumb;
+
+      try {
+        breadcrumbClone = structuredClone(bc);
+      } catch {
+        /**
+         * structuredClone may fail on non-cloneable values in breadcrumb.data
+         * Fall back to passing the original — hook may mutate it, but breadcrumb storage won't crash
+         */
+        breadcrumbClone = bc;
+      }
+
       const result = this.options.beforeBreadcrumb(breadcrumbClone, hint);
 
       /**
diff --git a/types/index.ts b/types/index.ts
index 1c4e801..ef93dd6 100644
--- a/types/index.ts
+++ b/types/index.ts
@@ -32,7 +32,7 @@ export interface HawkNodeJSInitialSettings {
    *
    * - Return modified event — it will be sent instead of the original.
    * - Return `false` — the event will be dropped entirely.
-   * - Return nothing (`void` / `undefined` / `null`) — the original event is sent as-is (a warning is logged).
+   * - Any other value is invalid — the original event is sent as-is (a warning is logged).
    */
   beforeSend?(event: EventData<NodeJSAddons>): EventData<NodeJSAddons> | false | void;
 

From cb8b6731b2131c71edfbafc6e32ae20c1f08244b Mon Sep 17 00:00:00 2001
From: Dobrunia Kostrigin <48620984+Dobrunia@users.noreply.github.com>
Date: Wed, 11 Feb 2026 20:17:15 +0300
Subject: [PATCH 6/7] fix: lint

---
 src/modules/breadcrumbs.ts | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/modules/breadcrumbs.ts b/src/modules/breadcrumbs.ts
index ccd7ce2..86d3077 100644
--- a/src/modules/breadcrumbs.ts
+++ b/src/modules/breadcrumbs.ts
@@ -30,7 +30,6 @@ export interface BreadcrumbsOptions {
    * - Return modified breadcrumb — it will be stored instead of the original.
    * - Return `false` — the breadcrumb will be discarded.
    * - Any other value is invalid — the original breadcrumb is stored as-is (a warning is logged).
-   *
    * @param breadcrumb - Breadcrumb to store (can be mutated and returned)
    * @param hint - Optional context (e.g. for filtering)
    */

From 4464ec0b1cdc28bf062cc90d8e604abb5ab55326 Mon Sep 17 00:00:00 2001
From: Dobrunia Kostrigin <48620984+Dobrunia@users.noreply.github.com>
Date: Wed, 11 Feb 2026 20:30:28 +0300
Subject: [PATCH 7/7] new test

---
 tests/before-send.test.ts | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/tests/before-send.test.ts b/tests/before-send.test.ts
index cacfdb9..1d08d23 100644
--- a/tests/before-send.test.ts
+++ b/tests/before-send.test.ts
@@ -161,6 +161,27 @@ describe('beforeSend processing', () => {
     expect(payload.backtrace).toBeInstanceOf(Array);
   });
 
+  it('still sends event when structuredClone throws (non-cloneable payload)', () => {
+    // Arrange
+    initWithBeforeSend((event) => event);
+    const cloneSpy = vi.spyOn(globalThis, 'structuredClone').mockImplementation(() => {
+      throw new DOMException('could not be cloned', 'DataCloneError');
+    });
+
+    // Act
+    HawkCatcher.send(new Error('non-cloneable'));
+
+    // Assert — event is still sent, reporting didn't crash
+    expect(axios.post).toHaveBeenCalledOnce();
+
+    const payload = getSentPayload();
+
+    expect(payload.title).toBe('Error: non-cloneable');
+    expect(payload.backtrace).toBeInstanceOf(Array);
+
+    cloneSpy.mockRestore();
+  });
+
   it('sends event without optional fields when beforeSend deletes them', () => {
     initWithBeforeSend((event) => {
       delete event.release;