feat(wrangler): improve script source display on pretty error screen by edmundhung · Pull Request #9971 · cloudflare/workers-sdk

edmundhung · 2025-07-15T13:46:02Z

Fixes DEVX-1974

Example screenshots:

Error from native module (Requrie "View All Frames" checked):
Error from missing source file (e.g. cookie)

Tests
- Tests included
- Tests not necessary because:
Public documentation
- Cloudflare docs PR(s):
- Documentation not necessary because: error screen is not documented
Wrangler V3 Backport
- Wrangler PR:
- Not necessary because: not bugfix

changeset-bot · 2025-07-15T13:46:06Z

🦋 Changeset detected

Latest commit: ae2bbd6

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 5 packages

Name	Type
wrangler	Minor
miniflare	Minor
@cloudflare/vite-plugin	Major
@cloudflare/vitest-pool-workers	Patch
@cloudflare/pages-shared	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

pkg-pr-new · 2025-07-15T13:48:37Z

create-cloudflare

npm i https://pkg.pr.new/create-cloudflare@9971

@cloudflare/kv-asset-handler

npm i https://pkg.pr.new/@cloudflare/kv-asset-handler@9971

miniflare

npm i https://pkg.pr.new/miniflare@9971

@cloudflare/pages-shared

npm i https://pkg.pr.new/@cloudflare/pages-shared@9971

@cloudflare/unenv-preset

npm i https://pkg.pr.new/@cloudflare/unenv-preset@9971

@cloudflare/vite-plugin

npm i https://pkg.pr.new/@cloudflare/vite-plugin@9971

@cloudflare/vitest-pool-workers

npm i https://pkg.pr.new/@cloudflare/vitest-pool-workers@9971

@cloudflare/workers-editor-shared

npm i https://pkg.pr.new/@cloudflare/workers-editor-shared@9971

wrangler

npm i https://pkg.pr.new/wrangler@9971

commit: ae2bbd6

edmundhung · 2025-07-16T11:22:57Z

We are now relying on the UserWorker miniflare instance to prettify the error so that we can retrieve the script source from its inspector.

edmundhung · 2025-07-16T11:25:55Z

We will continue stripping this header by default, except on the ProxyWorker miniflare which will pass the header over to the UserWorker miniflare so that user can disable the pretty error screen when needed.

edmundhung · 2025-07-16T11:36:37Z

Youch currently skip displaying the script source if it is an internal module. But we do want it to show up if frame.source is defined. I will put up a PR to youch later.

edmundhung · 2025-07-16T11:41:54Z

+       return "";
+     }
+-    const language = LANGS_MAP[extname(frame.fileName)] ?? "plain";
+    const language = LANGS_MAP[extname(frame.fileName)] ?? (frame.type === "native" ? "js" : "plain");


Native modules have no extension so there is no syntax highlight by default. But it should be safe to assume native modules to be javascript if available?

edmundhung · 2025-07-16T11:43:15Z

+   #getEditorLink(ide, frame) {
+     const editorURL = EDITORS[ide] || ide;
+-    if (!editorURL || frame.type === "native") {
+    if (!editorURL || frame.type === "native" || !existsSync(frame.fileName)) {


Not sure if this is a good patch upstream as it assumes youch is running on node environment only. But I will raise it up when I submit a PR to youch.

Can we make this optional so it can run in non-node environments? We run Youch ourselves in a non-node environment (format-errors), so it would be nice to make that possible without patches (that we apply to format-errors)

penalosa · 2025-07-18T12:21:58Z

+   #getEditorLink(ide, frame) {
+     const editorURL = EDITORS[ide] || ide;
+-    if (!editorURL || frame.type === "native") {
+    if (!editorURL || frame.type === "native" || !existsSync(frame.fileName)) {


Can we make this optional so it can run in non-node environments? We run Youch ourselves in a non-node environment (format-errors), so it would be nice to make that possible without patches (that we apply to format-errors)

edmundhung · 2025-07-21T12:35:26Z

+   #getEditorLink(ide, frame) {
+     const editorURL = EDITORS[ide] || ide;
+-    if (!editorURL || frame.type === "native") {
+    if (!editorURL || frame.type === "native" || frame.fileType !== 'fs') {


We are now relying on the fileType to decide whether Youch should generate a link.

workers-devprod added this to workers-sdk Jul 15, 2025

github-project-automation Bot moved this to Untriaged in workers-sdk Jul 15, 2025

edmundhung force-pushed the edmundhung/DEVX-1974 branch from b690074 to 016388b Compare July 16, 2025 10:26

edmundhung changed the title ~~feat: improve source display on pretty error page~~ feat(wrangler): improve script source display on pretty error screen Jul 16, 2025

edmundhung force-pushed the edmundhung/DEVX-1974 branch from 016388b to f0007b3 Compare July 16, 2025 11:28

feat(wrangler): improve script source display on pretty error screen

e04e371

edmundhung force-pushed the edmundhung/DEVX-1974 branch from f0007b3 to e04e371 Compare July 16, 2025 11:39

edmundhung commented Jul 16, 2025

View reviewed changes

edmundhung marked this pull request as ready for review July 16, 2025 11:58

edmundhung requested a review from a team as a code owner July 16, 2025 11:58

edmundhung requested a review from penalosa July 16, 2025 11:58

penalosa reviewed Jul 18, 2025

View reviewed changes

edmundhung added 2 commits July 21, 2025 13:06

avoid relying on fs in the patch with style refined

b99839b

drop native module script source support

ae2bbd6

edmundhung commented Jul 21, 2025

View reviewed changes

penalosa approved these changes Jul 23, 2025

View reviewed changes

github-project-automation Bot moved this from Untriaged to Approved in workers-sdk Jul 23, 2025

edmundhung merged commit 19794bf into main Jul 23, 2025
48 of 50 checks passed

edmundhung deleted the edmundhung/DEVX-1974 branch July 23, 2025 12:50

github-project-automation Bot moved this from Approved to Done in workers-sdk Jul 23, 2025

workers-devprod mentioned this pull request Jul 23, 2025

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feat(wrangler): improve script source display on pretty error screen - #9971

feat(wrangler): improve script source display on pretty error screen#9971
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