(fix) App crashes when no unseen messages retrieved

Description:
The app currently crashes when no unseen messages are retrieved from the user's mailbox, because the app attempts to call .length on an undefined variable.

Fix:
Check for "no messages today" edge case before attempting to process messages

Testcase:
1)  Clear messages from test user's inbox
2)  Log into mail crunch
3)  Verify "You have 0 new messages" is displayed
4)  Verify user redirected to /crunch page