[FUSE] Catch and recover from any API client exceptions
#5896 caused an API client error (timeout) to be raised in arv-mount. This exception was ultimately uncaught, and caused arv-mount to crash. arv-mount should never crash because of a problem talking to the API server.
- Figure out what exceptions an API client call can raise. (Node Manager has some opinions about this.)
- Make sure any time an API call is made, the exception is caught and handled appropriately, by reporting an error to FUSE, then go back to the main loop.