Improve exception handling
Currently, most exceptions thrown by SabreDAV are caught directly in the methods that call SabreDAV. This is not ideal, as some methods rely on the exceptions to tell if their operation succeeded or not (e.g. the copy and move methods).
We should identify all methods in the driver that possibly raise exceptions, identify which exceptions can be raised, and react accordingly. Ideally, all exceptions that are related to some user input are passed to higher (maybe with different exception classes, like in the copy and move methods), while all that show a permanent error (configuration etc.) are used to warn an admin.
This issue will require changes in the TYPO3 core to be fully resolved.