Improve error message for Graphql API (#7805)

![CleanShot 2024-10-17 at 11 39
39](https://github.com/user-attachments/assets/616b8317-de1f-4b61-b2b4-980b14b09f66)

This improves this error message.

---------

Co-authored-by: Félix Malfait <felix@twenty.com>

packages/twenty-server/src/engine/decorators/auth/auth-user.decorator.ts

@@ -15,7 +15,9 @@ export const AuthUser = createParamDecorator(
     const request = getRequest(ctx);
 
     if (!options?.allowUndefined && !request.user) {
-      throw new ForbiddenException("You're not authorized to do this");
+      throw new ForbiddenException(
+        "You're not authorized to do this. Note: This endpoint requires a user and won't work with just an API key.",
+      );
     }
 
     return request.user;