How to change the error message when an endpoint errors?

[TechplexEngineer]

For example if I have an endpoint with this get handler:

export const get: RequestHandler = async () => {
	return {
		status: 400,
		body: new Error("Not yet implemented")
	};
};

The frontend shows a stack trace prefixed with "Failed to load data". How can I change the error message?

[mustofa-id]

Can't see this in latest version of Kit.