MAINT: wrote API errors to console.

[Carreau]

Sending the error to the frontend does not preclude to writing it to the console. When the frontend does not work the error is logged nowhere, and therefore having it persisted in the log can be helpful.

[blink1073]

As far as I can tell we're already logging tracebacks for API errors:

With this change (I had to change exec_info -> exc_info:

[E 2022-11-10 12:24:31.113 ServerApp] Uncaught exception POST /api/sessions?1668104671111 (127.0.0.1)
    HTTPServerRequest(protocol='http', host='localhost:8888', method='POST', uri='/api/sessions?1668104671111', version='HTTP/1.1', remote_ip='127.0.0.1')
    Traceback (most recent call last):
      File "/Users/silvester/workspace/.venvs/jupyter_server/lib/python3.10/site-packages/tornado/web.py", line 1713, in _execute
        result = await result
      File "/Users/silvester/workspace/jupyter_server/jupyter_server/services/sessions/handlers.py", line 55, in post
        raise ValueError('what')
    ValueError: what
[E 2022-11-10 12:24:31.115 ServerApp] wrote error: 'Unhandled error'
    Traceback (most recent call last):
      File "/Users/silvester/workspace/.venvs/jupyter_server/lib/python3.10/site-packages/tornado/web.py", line 1713, in _execute
        result = await result
      File "/Users/silvester/workspace/jupyter_server/jupyter_server/services/sessions/handlers.py", line 55, in post
        raise ValueError('what')
    ValueError: what
[E 2022-11-10 12:24:31.115 ServerApp] {
      "Host": "localhost:8888",
      "Accept": "*/*",
      "Referer": "http://localhost:8888/notebooks/Untitled.ipynb?factory=Notebook",
      "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:105.0) Gecko/20100101 Firefox/105.0"
    }
[E 2022-11-10 12:24:31.115 ServerApp] 500 POST /api/sessions?1668104671111 (dc85ee701ce14062bbb2359cbe9dc4f4@127.0.0.1) 2.86ms referer=http://localhost:8888/notebooks/Untitled.ipynb?factory=Notebook

Before this change:

[E 2022-11-10 12:26:41.730 ServerApp] Uncaught exception POST /api/sessions?1668104801728 (127.0.0.1)
    HTTPServerRequest(protocol='http', host='localhost:8888', method='POST', uri='/api/sessions?1668104801728', version='HTTP/1.1', remote_ip='127.0.0.1')
    Traceback (most recent call last):
      File "/Users/silvester/workspace/.venvs/jupyter_server/lib/python3.10/site-packages/tornado/web.py", line 1713, in _execute
        result = await result
      File "/Users/silvester/workspace/jupyter_server/jupyter_server/services/sessions/handlers.py", line 55, in post
        raise ValueError('what')
    ValueError: what
[W 2022-11-10 12:26:41.733 ServerApp] wrote error: 'Unhandled error'
[E 2022-11-10 12:26:41.733 ServerApp] {
      "Host": "localhost:8888",
      "Accept": "*/*",
      "Referer": "http://localhost:8888/notebooks/Untitled.ipynb?factory=Notebook",
      "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:105.0) Gecko/20100101 Firefox/105.0"
    }
[E 2022-11-10 12:26:41.733 ServerApp] 500 POST /api/sessions?1668104801728 (dc85ee701ce14062bbb2359cbe9dc4f4@127.0.0.1) 2.68ms referer=http://localhost:8888/notebooks/Untitled.ipynb?factory=Notebook

[Carreau]

Hum, this is strange, because I definitely had errors without any traceback. I'll recheck.

[Carreau]

Let's close this for now to limit the number of opened PRs.