I cloned your form to test it, setup the esign widget with my test account and everything appeared to work properly. After entering my email address in the widget, I was presented with the pop-up for the signature process:
However, when I test your copy, I do indeed get the "Something's Wrong" error.
Try replacing the widget with a new copy and authenticating once again. The widget should be working with a properly authenticated account.
Here is my test form so you can see it working:
If it still does not work after replacing it with a new copy, let us know and we will be happy to have another look.