From b7a0e50b920961aac4d29619f721a4f915221df1 Mon Sep 17 00:00:00 2001
From: James Johnson <james.johnson@tiny.cloud>
Date: Fri, 18 Jul 2025 12:15:03 +1000
Subject: [PATCH] TINY-12536: Loader catches and reports errors from
 `tinymce.init` (#10473)

---
 .../mcagar-TINY-12536-2025-07-16.yaml         |  6 +++
 .../src/main/ts/ephox/mcagar/loader/Loader.ts | 54 ++++++++++---------
 2 files changed, 35 insertions(+), 25 deletions(-)
 create mode 100644 .changes/unreleased/mcagar-TINY-12536-2025-07-16.yaml

diff --git a/.changes/unreleased/mcagar-TINY-12536-2025-07-16.yaml b/.changes/unreleased/mcagar-TINY-12536-2025-07-16.yaml
new file mode 100644
index 0000000000..806a73633f
--- /dev/null
+++ b/.changes/unreleased/mcagar-TINY-12536-2025-07-16.yaml
@@ -0,0 +1,6 @@
+project: mcagar
+kind: Fixed
+body: Loader will catch errors thrown by `tinymce.init` and report them to the caller.
+time: 2025-07-16T14:36:55.407731349+10:00
+custom:
+    Issue: TINY-12536
diff --git a/modules/mcagar/src/main/ts/ephox/mcagar/loader/Loader.ts b/modules/mcagar/src/main/ts/ephox/mcagar/loader/Loader.ts
index 32d5c9c666..5560e0df03 100644
--- a/modules/mcagar/src/main/ts/ephox/mcagar/loader/Loader.ts
+++ b/modules/mcagar/src/main/ts/ephox/mcagar/loader/Loader.ts
@@ -1,5 +1,5 @@
 import { TestLogs } from '@ephox/agar';
-import { Arr, Fun, FutureResult, Global, Id, Optional, Result } from '@ephox/katamari';
+import { Arr, Fun, FutureResult, Global, Id, Optional, Result, Type } from '@ephox/katamari';
 import { Attribute, DomEvent, Insert, Remove, SelectorFilter, SugarBody, SugarElement, SugarHead, SugarShadowDom } from '@ephox/sugar';
 
 import { Editor } from '../alien/EditorTypes';
@@ -74,7 +74,8 @@ const setup = (callbacks: Callbacks, settings: Record<string, any>, elementOpt:
   };
 
   // Agar v. ??? supports logging
-  const onFailure = (err: Error | string, logs?: TestLogs) => {
+  const onFailure = (errU: unknown, logs?: TestLogs) => {
+    const err = Type.isString(errU) || errU instanceof Error ? errU : String(errU);
     // eslint-disable-next-line no-console
     console.log('Tiny Loader error: ', err);
     // Do no teardown so that the failed test still shows the editor. Important for selection
@@ -88,31 +89,34 @@ const setup = (callbacks: Callbacks, settings: Record<string, any>, elementOpt:
     callbacks.preInit(tinymce, settings);
 
     const targetSettings = SugarShadowDom.isInShadowRoot(target) ? ({ target: target.dom }) : ({ selector: '#' + randomId });
+    try {
+      Promise.resolve(tinymce.init({
+        promotion: false,
+        license_key: 'gpl',
+        ...settings,
+        ...targetSettings,
+        setup: (editor: Editor) => {
+          // Execute the setup called by the test.
+          settingsSetup(editor);
 
-    tinymce.init({
-      promotion: false,
-      license_key: 'gpl',
-      ...settings,
-      ...targetSettings,
-      setup: (editor: Editor) => {
-        // Execute the setup called by the test.
-        settingsSetup(editor);
+          editor.once('SkinLoaded', () => {
+            setTimeout(() => {
+              try {
+                callbacks.run(editor, onSuccess, onFailure);
+              } catch (e: any) {
+                onFailure(e);
+              }
+            }, 100);
+          });
 
-        editor.once('SkinLoaded', () => {
-          setTimeout(() => {
-            try {
-              callbacks.run(editor, onSuccess, onFailure);
-            } catch (e: any) {
-              onFailure(e);
-            }
-          }, 100);
-        });
-
-        editor.once('SkinLoadError', (e) => {
-          callbacks.failure(e.message);
-        });
-      }
-    });
+          editor.once('SkinLoadError', (e) => {
+            callbacks.failure(e.message);
+          });
+        }
+      })).catch(onFailure);
+    } catch (err: unknown) {
+      onFailure(err);
+    }
   };
 
   if (!Global.tinymce) {