I had this old jQuery UI slider that had worked just fine a few months ago, but now I seem to be getting an exception reading: Cannot call method \'addClass\' of undefined.
I solved this error by using integers in "min", "max" and "values". Maybe you are setting null values.
The jQuery Slider specification says:
max Number Default:100 min Number Default:0 value Number Default: 0
So "values" are an array of numbers.