Uncaught TypeError: Cannot use 'in' operator to search for 'length' in 0
I found the solution in this thread on the .org forum. The problem has to do with jQuery 1.11.3 and the solution is to simply replace
wp-includes/js/jquery/jquery.js with jQuery 1.11.0 for example. Any other version besides 1.11.3 or 2.1.4 would do the trick!