Appointments+ datepicker jquery doesn't throws error


When I click on the appointments picker ( , 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).