Create a general error handler which handles multiple errors

Introduce a general error handler which displays errors using a SnackBar one after each other ([following the Material guidelines](https://m3.material.io/components/snackbar/guidelines#84cd5bb6-354f-4fd0-bdd9-daf9684ba4bf)).

Context: https://github.com/android/nowinandroid/pull/1090

Start by reviewing the linked pull request 1090 and the Material Snackbar guidelines. Then locate the existing error-display flow in the app and determine how errors are currently surfaced. Done means multiple errors are handled by a general mechanism and displayed one after another in SnackBars according to the stated guidelines.

Written by the indexing model from the issue text.