If a moderator tries to delete a comment of a user that is not a member on the site (because the question was migrated) then the Android app crashes (app version 1.0.77).
The bug can be reproduced consistently.
Update January 14, 2020: I'm now using Android app version 1.0.95 and noticed this bug still/again is present. The app crashes every time I try to delete a comment written by people that are not a member on the site (migrated question). I tried it with 3 different users, all non-members at the time of writing, and get the same behavior every time.