Fix getMenuNode() for leaf nodes (#15845)

Fixes #15828

Contributed on behalf of STMicroelectronics

Signed-off-by: Thomas Mäder <t.s.maeder@gmail.com>

Author: tsmaeder

packages/core/src/browser/menu/menu.spec.ts

@@ -50,7 +50,6 @@ class TestMenuNodeFactory implements MenuNodeFactory {
 }
 
 describe('menu-model-registry', () => {
-
     describe('01 #register', () => {
         it('Should allow to register menu actions.', () => {
             const fileMenu = ['main', 'File'];
@@ -86,6 +85,9 @@ describe('menu-model-registry', () => {
             const openGroup = file.children[0] as Submenu;
             expect(openGroup.children.length).equals(2);
             expect(openGroup.label).undefined;
+
+            expect(service.getMenuNode([...fileOpenMenu, 'open'])).exist;
+            expect(service.getMenuNode([...fileOpenMenu, 'Gurkensalat'])).undefined;
         });
 
         it('Should not allow to register cyclic menus.', () => {

packages/core/src/common/menu/menu-model-registry.ts

@@ -311,13 +311,15 @@ export class MenuModelRegistry {
         }
     }
 
-    protected findInNode(root: CompoundMenuNode, menuPath: MenuPath, pathIndex: number): MenuNode | undefined {
+    protected findInNode(root: MenuNode, menuPath: MenuPath, pathIndex: number): MenuNode | undefined {
         if (pathIndex === menuPath.length) {
             return root;
         }
-        const child = root.children.find(c => c.id === menuPath[pathIndex]);
-        if (CompoundMenuNode.is(child)) {
-            return this.findInNode(child, menuPath, pathIndex + 1);
+        if (CompoundMenuNode.is(root)) {
+            const child = root.children.find(c => c.id === menuPath[pathIndex]);
+            if (child) {
+                return this.findInNode(child, menuPath, pathIndex + 1);
+            }
         }
         return undefined;
     }