diff --git a/services/web/frontend/js/features/source-editor/components/editor-switch.tsx b/services/web/frontend/js/features/source-editor/components/editor-switch.tsx
index c83eeef357..092e4563a9 100644
--- a/services/web/frontend/js/features/source-editor/components/editor-switch.tsx
+++ b/services/web/frontend/js/features/source-editor/components/editor-switch.tsx
@@ -17,7 +17,7 @@ function EditorSwitch() {
   const richTextAvailable = openDocName
     ? isVisualEditorAvailable(openDocName)
     : false
-  const extension = getFileExtension(openDocName || '')
+  const extension = getFileExtension(openDocName || '') ?? ''
 
   const handleChange = useCallback(
     (event: ChangeEvent<HTMLInputElement>) => {