Attempt to show notification of library sync error (fixes #3848)

[slideclimb]

Fix #3848

Summary of additions and changes

Attempts to not fail without notification when getting an unexpected response from a remote library.

How to test this pull request

I'm not sure how to trigger an error, but have verified that logging into Mendeley and syncing the library still works.

• Updated the documentation, or no update necessary
• Added tests, or no tests necessary

[PHPirates]

I could reproduce the exception a couple of times, but not reliably. The cause is an invalid token error, I think when there is no token present in the password safe. Added a try catch in the correct place to convert the exception into a notification