Create a general error handler which handles multiple errors

[dturner]

Introduce a general error handler which displays errors using a SnackBar one after each other (following the Material guidelines).

Context: #1090

[Jaehwa-Noh]

This is out of the context, but we should consider that offline warning SnackBar also. Under the Material guidelines we can't display any error message because offline warning SnackBar takes a place permanently.

Maybe we should change the method how we display the offline warning.
#350 (comment)