Handle thrown exceptions consistently with other frameworks

[anniefu]

There are two scenarios where Node behaves different from most other Functions Frameworks

1. User throws an exception in their function code
2. User returns an error in their event-driven function code (HTTP functions don't have return parameters)

Most frameworks will return HTTP status code 500 in both those cases, and hide the exception/error message from the invoker.

Node returns 200 status code and returns the exception/error message in the response body. We should modify node to return 500 and omit the exception/error message from the response body to avoid leaking debug information to the invoker. We should log the message instead.

[grant]

Correct. I'm seeing a 200 error being sent in Node.

/**
 * Send "Hello, World!"
 * @param req https://expressjs.com/en/api.html#req
 * @param res https://expressjs.com/en/api.html#res
 */
exports.helloWorld = (req, res) => {
  throw new Error('hi');
  res.send('Hello, World!');
};

Response:

HTTP/1.1 200 OK
X-Google-Status: crash
Content-Type: text/html; charset=utf-8
Content-Length: 2
ETag: W/"2-witfkXg0JglCjW9RssWvTAveakI"
Date: Thu, 03 Feb 2022 20:51:26 GMT
Connection: keep-alive
Keep-Alive: timeout=5

Expected:

HTTP/1.1 500 Internal Server Error
X-Google-Status: crash
Content-Type: text/html; charset=utf-8
Content-Length: 2
ETag: W/"2-witfkXg0JglCjW9RssWvTAveakI"
Date: Thu, 03 Feb 2022 20:48:32 GMT
Connection: keep-alive
Keep-Alive: timeout=5

Location of sending error:

https://github.com/GoogleCloudPlatform/functions-framework-nodejs/blob/master/src/logger.ts#L46

I believe we can simply do a:

res.status(500);

[grant]

May need another pair of eyes to understand the failures / expected result.