possible bug in jquery ui's slider class and closestHandle? Cannot call method 'addClass' of undefined

jquery-ui-1.8.23-orig.js

	_mouseCapture: function( event ) {	
          	var o = this.options,
			position,
			normValue,
			distance,
			closestHandle,
			self,
			index,
			allowed,
			offset,
			mouseOverHandle;

		if ( o.disabled ) {
			return false;
		}

		this.elementSize = {
			width: this.element.outerWidth(),
			height: this.element.outerHeight()
		};
		this.elementOffset = this.element.offset();

		position = { x: event.pageX, y: event.pageY };
		normValue = this._normValueFromMouse( position );
		distance = this._valueMax() - this._valueMin() + 1;
		self = this;
		this.handles.each(function( i ) {
			var thisDistance = Math.abs( normValue - self.values(i) );
			if ( distance > thisDistance ) {
				distance = thisDistance;
				closestHandle = $( this );
				index = i;
			}
		});

		// workaround for bug #3736 (if both handles of a range are at 0,
		// the first is always used as the one with least distance,
		// and moving it is obviously prevented by preventing negative ranges)
		if( o.range === true && this.values(1) === o.min ) {
			index += 1;
			closestHandle = $( this.handles[index] );
		}

                // --- >8 --- >8 --- >8 --- >8 ---
                //
                // HERE'S MY FIX, FROM @TLACK
		// fell through all other attempts? find at least the first 
		// handle..
		if (!closestHandle) {
			index = 0;
			closestHandle = $( this.handles[index] );
		}
                // 
                // --- >8 --- >8 --- >8 --- >8 ---

		allowed = this._start( event, index );
		if ( allowed === false ) {
			return false;
		}
		this._mouseSliding = true;

		self._handleIndex = index;

		closestHandle
			.addClass( "ui-state-active" )
			.focus();
		
		offset = closestHandle.offset();
		mouseOverHandle = !$( event.target ).parents().andSelf().is( ".ui-slider-handle" );
		this._clickOffset = mouseOverHandle ? { left: 0, top: 0 } : {
			left: event.pageX - offset.left - ( closestHandle.width() / 2 ),
			top: event.pageY - offset.top -
				( closestHandle.height() / 2 ) -
				( parseInt( closestHandle.css("borderTopWidth"), 10 ) || 0 ) -
				( parseInt( closestHandle.css("borderBottomWidth"), 10 ) || 0) +
				( parseInt( closestHandle.css("marginTop"), 10 ) || 0)
		};

		if ( !this.handles.hasClass( "ui-state-hover" ) ) {
			this._slide( event, index, normValue );
		}
		this._animateOff = true;
		return true;
	},

I made below changes to jquery-ui.js file and that fixed my issue and everything is working smoothly.

                    this.handles.each(function(i) {
                        var thisDistance = Math.abs(normValue - that.values(i));
                        if (!thisDistance)
                            thisDistance = 0;
                        if ((distance > thisDistance) ||
            (distance === thisDistance &&
                (i === that._lastChangedValue || that.values(i) === o.min))) {
                            distance = thisDistance;
                            closestHandle = $(this);
                            index = i;
                        }
                    });
                    if (o.range === true && this.values(1) === o.min) {
                        index += 1;
                        closestHandle = $(this.handles[index]);
                    }
                    allowed = this._start(event, index);
                    if (allowed === false) {
                        return false;
                    }
                    this._mouseSliding = true;

                    this._handleIndex = index;
                    closestHandle
                        .addClass("ui-state-active")
                        .focus();

Do you have some decimal values like .5 in your min, max, value value?
Once I changed it to 0.5, it worked