message: Alter the error message for webhook payloads that are not JSON.
diff: @@ -37,7 +37,7 @@ function extractWebhookData(req: Req, body?: string): WebhookRequestData {
  try {
  bodyObj = body == null || body === '' ? {} : JSON.parse(body);
  } catch (e) {
  - throw new Error(`request body is not parsable as JSON: ${e}`);
  + throw new Error(`Request body is not parsable as JSON. Are you sure you have enabled application/json as the webhook content type? ${e}.`);
  }
  if ('x-github-event' in req.headers) {
  