Appointments+ datepicker jquery doesn't throws error

Hello,

When I click on the appointments picker (http://puu.sh/kBF1M/2b75a314ae.jpg) , it used to open up a window to the right where it'd show the times. But now it doesn't anymore and it throws this error in the console;
Uncaught TypeError: Cannot read property 'createDocumentFragment' of null

It literally worked two hours ago, and now the client replied that it doesn't work when they tested it (and it doesn't).

Thanks,
Wouter