Calendars / Show error message and backtrace when synchronization fails #3989
Description
When calendar synchronization fails the UI is not showing any error message, an admin can only notice when was happened the last successful sync.
It could be very useful to:
- show the last sync timestamp and the status (failed or success)
- if it failed, include a backtrace of the error for debugging purposes. The backtrace could consist in the error message and a collapsed text with the rest of the backtrace.