Return appropriate HTTP statuscode on OCA\Notes\Service\NoteDoesNotExistException

[stefan-niedermann]

Currently HTTP 500 is returned from the server, in case that a client wants to PUT a locally modified note which does no more exist on the server.

Some potential candidates:

• 412 Precondition Failed The server does not meet one of the preconditions that the requester put on the request header fields.
• 409 Conflict Indicates that the request could not be processed because of conflict in the current state of the resource, such as an edit conflict between multiple simultaneous updates.
• 404 Not Found The requested resource could not be found but may be available in the future. Subsequent requests by the client are permissible.
• 400 Bad Request The server cannot or will not process the request due to an apparent client error

The candy on the ice cream would be a 410 Gone if the file is in the trashbin.

[korelstar]

Good point. I think we should use 404.