If selectedText.length is 0, undefined judgment is made.

apps/app/src/features/openai/client/services/editor-assistant.ts

@@ -119,7 +119,9 @@ export const useEditorAssistant: UseEditorAssistant = () => {
       body: JSON.stringify({
         threadId,
         userMessage,
-        markdown: selectedText,
+        markdown: selectedText != null && selectedText.length !== 0
+          ? selectedText
+          : undefined,
       }),
     });