Fix error when we try to unbind an event whose type has never been bound before
Fix error when we try to unbind an event whose type has never been bound before

maciekwie/Crafty,mucaho/Crafty,craftyjs/Crafty,maciekwie/Crafty,craftyjs/Crafty,craftyjs/Crafty,starwed/Crafty,mucaho/Crafty,starwed/Crafty,maciekwie/Crafty,starwed/Crafty,mucaho/Crafty