/**
 * Generates an HTTP error response based on the request's "Accept" header.
 *
 * If the "Accept" header includes "text/html" and debugging is enabled, it returns
 * an HTML response with the error message and stack trace.
 *
 * If the "Accept" header includes "application/json" or debugging is enabled, it
 * returns a JSON response with the error message and optionally the stack trace.
 *
 * Otherwise, it returns a plain text response indicating an internal server error.
 *
 * @param error - The error object or message to include in the response.
 * @param req - The incoming HTTP request object.
 * @param debug - A boolean indicating whether debugging information should be included.
 * @returns A Response object with the appropriate error details and status code.
 */
export declare function errorResponse(error: unknown, req: Request, debug: boolean): Response;