fails:Array#delete_at removes the element at the specified index
fails:Array#delete_at returns nil and makes no modification if the index is out of range
fails:Array#delete_at tries to convert the passed argument to an Integer using #to_int
fails:Array#delete_at raises a RuntimeError on a frozen array
fails:Array#delete_at keeps tainted status
fails:Array#delete_at keeps untrusted status
