Summary:

When calling $(...).draggable("destroy") the following line will throw an error:

ui.draggable.js(77): this.handle.removeMouseInteraction();

The error states that "this.handle" has no properties. Upon inspection it appears to be that "this.handle" is undefined.

Possible Solution:

Looks like it should be referring to "this.options.handle" instead of "this.handle".

I made the change on my local code and it appears to work as expected.