message: backend-common: use explicit content type in error response
diff: @@ -63,10 +63,10 @@ export function errorHandler(
  return (
  error: Error,
  _request: Request,
  - response: Response,
  + res: Response,
  next: NextFunction,
  ) => {
  - if (response.headersSent) {
  + if (res.headersSent) {
  // If the headers have already been sent, do not send the response again
  // as this will throw an error in the backend.
  next(error);
  @@ -80,7 +80,9 @@ export function errorHandler(
  logger.error(error);
  }
  - response.status(status).send(message);
  + res.status(status);
  + res.setHeader('content-type', 'text/plain');
  + res.send(message);
  };
  }
  