Fixed a bug where if you had an event open on two seperate screens and
deleted the same tag on both - the tag list would crash and you would
never be able to get all the tags for that event again. Before it only
checked to make sure the tag existed for the user, but now it checks for
that specific event that you are trying to delete from so it wont say
the tag could be there when it isnt actually on that event - its on a
different event