Strange Bug

I've found some kind of bug to do with deleting a tag then deleting a
gif and searching through favourites, but I don't even have enough of an
idea of what the process is to replicate it exactly - the main thing I
know is that it ends up creating a null value in the users favourite gif
array. Suddenly just thinking that it actually could do with speed -
when a search is immediately made before mongo has had a chance to
delete the null value from the array...
Still can't replicate bug exactly, add to github

strange