[Bug] "Filtered list empty" is not a failure

[rptb1]

Description If a schedule filter produces an empty list, NeoBackup reports the backup as falling, but there is no actual error or failure. The backup succeeded. Also, the error notification does not include the schedule name.

Steps To Reproduce

1. Create a schedule of e.g. "new and updated apps".
2. Don't add or update any apps.
3. Let the schedule run.
4. Notification says backup failed and doesn't say which schedule it's taking about.

Expected behavior An empty backup is a success. Nothing went wrong.

Screenshots

System Information(please complete the following information):

• Device: Fairphone 3
• Android Version: LineageOS for microG 20
• ROM: (AOSP, MIUI, OOS...)
• App's Version: 8.3.1 via F-Droid