Notify error to user

[opatry]

Description

• ✅ Expose user actions leading to error in an event flow
• ✅ Display error event as Snackbar
• ❌ no retry mechanism (left for later in Notify user about error #115)
• ❌ no error cause analysis (like no network for instance) (left for later in Notify user about error #115)

Checklist

• I have read the CONTRIBUTING guide
• Code compiles correctly
• Created tests which fail without the change (if possible)
• All tests passing