feat(ckeditor/watchdog): ignore parent check (closes #5776)

packages/ckeditor5/src/custom_watchdog.ts

@@ -0,0 +1,20 @@
+import { CKEditorError, EditorWatchdog } from "ckeditor5";
+
+const IGNORED_ERRORS = [
+    // See: https://github.com/TriliumNext/Trilium/issues/5776
+    "TypeError: Cannot read properties of null (reading 'parent')"
+]
+
+export default class CustomWatchdog extends EditorWatchdog {
+
+    _isErrorComingFromThisItem(error: CKEditorError): boolean {
+        for (const ignoredError of IGNORED_ERRORS) {
+            if (error.message.includes(ignoredError)) {
+                return false;
+            }
+        }
+
+        return super._isErrorComingFromThisItem(error);
+    }
+
+}