Argument 1 passed to `OCA\\Text\\Service\\DocumentService: :getFileForSession()` must be an instance of `OCA\\Text\\Db\\Session`

[azul]

Describe the bug
https://github.com/nextcloud/text/blob/master/lib/Service/DocumentService.php#L376 expects a session.

https://github.com/nextcloud/text/blob/master/lib/Service/ApiService.php#L141-L142 might call it without one if the session cannot be found.

Either prevent this by checking for a valid session first like the sync function does or handle the case that getSession returns false.

[juliusknorr]

I'd say indeed checking for isValidSession as the very first action makes sense here.

[juliusknorr]

There is also no additional overhead then since the session is cached for the request:

text/lib/Service/SessionService.php

Line 159 in 518c2e9

if ($this->session !== null) {

[azul]

I think the API of the SessionService is not ideal. Maybe we could combine getSession and isValidSession in a way that one can only get a valid session or else an exception will be thrown.