JSON request finishes with non-json response

[dev-dsp]

jupyter_server/jupyter_server/services/contents/handlers.py

Lines 111 to 115 in 4ee6e1d

	async def _finish_error(self, code, message):
	"""Finish a JSON request with an error code and descriptive message"""
	self.set_status(code)
	self.write(message)
	await self.finish()

[dev-dsp]

Worst thing is that

resp.headers
{'server': 'TornadoServer/6.4', 'content-type': 'application/json'

resp.content
b"file or directory '/my.txt' does not exist"

[dev-dsp]

Worked around with

from jupyter_server.services.contents.handlers import ContentsHandler, json, json_default, path_regex

# ContentsHandler fixed to actually respond with JSON on errors
class ContentsHandlerFixed(ContentsHandler):
    async def _finish_error(self, code, message):
        """Finish a JSON request with an error code and descriptive JSON message"""
        #                                                           ^^^^
        await super()._finish_error(code, json.dumps(message, default=json_default))


default_handlers = [
    (r"/api/contents%s" % path_regex, ContentsHandlerFixed),
]

c.ServerApp.extra_services = [
  "contents_handler_fixed"
]

[dev-dsp]

I'd rather expect HTTP errors to be handled in either a more centralized way (such as a common method in a parent class) or a couple of layers above the final endpoint handler (server_app or Tornado web app).