Error: Assertion failed: x should be a finite number
at window.assertions.assertFunction (http://phettest.colorado.edu/assert/js/assert.js:23:13)
at HSliderThumb.translate (http://phettest.colorado.edu/scenery/js/nodes/Node.js?bust=1479837330859:1726:19)
at HSliderThumb.setCenterX (http://phettest.colorado.edu/scenery/js/nodes/Node.js?bust=1479837330859:2324:12)
at HSliderThumb.set centerX [as centerX] (http://phettest.colorado.edu/scenery/js/nodes/Node.js?bust=1479837330859:2327:33)
at Array.valueObserver (http://phettest.colorado.edu/sun/js/HSlider.js?bust=1479837330859:238:21)
at Emitter.emit2 (http://phettest.colorado.edu/axon/js/Emitter.js?bust=1479837330859:139:49)
at Property._notifyObservers (http://phettest.colorado.edu/axon/js/Property.js?bust=1479837330859:170:29)
at Property._setAndNotifyObservers (http://phettest.colorado.edu/axon/js/Property.js?bust=1479837330859:158:14)
at Property.set (http://phettest.colorado.edu/axon/js/Property.js?bust=1479837330859:126:16)
at http://phettest.colorado.edu/wave-on-a-string/js/wave-on-a-string/view/control/slider/Slider.js?bust=1479837330859:108:28