NaN instead of the number of unread notifications
### Expected Behavior
When the Sleekplan widget button appears it should have a badge with the number of unread notifications or no badge.
### Current Behavior
When the sleekplan widget button is displayed, a NaN (Not a Number?) badge appears where the number of unread notifications should appear.
### Possible Solution
Validate that the number of unread notifications is a valid number and if it is not, do not display the medal
### Steps to Reproduce
Sign in with a new user on a board that already has a few posts
### Context (Environment)
This bug is affecting my productive environment and has already been noticed by some users