Whenever I tap the first comment on this answer (by user221081) in an attempt to upvote it, the Android app crashes. I can reproduce this consistently; I've also sent a report.
Nexus 5, Android 5.0.1 (Lollipop), Stack Exchange app 1.0.51.
On today's edition of "Kasra hates the convoluted
if statements he wrote": Did you think an
Integer type can be null?!?
We were using that for maintaining user ids, and since user221081 doesn't have a real user id since it's a comment not belonging to a real user on this site... you can guess the rest.
Thanks for catching this! It's fixed as of the next update (1.0.53+)