Don't crash if the user long-presses on the bottom of the list.
Don't crash if the user long-presses on the bottom of the list.

Closes trac #911.

prati0100/zulip-android,saketkumar95/zulip-android,Sam1301/zulip-android,vishwesh3/zulip-android,saketkumar95/zulip-android,Sam1301/zulip-android,prati0100/zulip-android,abhaymaniyar/zulip-android,abhaymaniyar/zulip-android,zulip/zulip-android