After refreshing a chart by using a dispose() method followed by redefining and recreating the fusionchart I'm getting the following warning when hovering or moving the cursor over the 'updated' chart.:
Uncaught TypeError: this._env is undefined
This is on line 13 of fusioncharts.js
This is for version 3.15.2.
Seems that the function is falsely assuming that the value exists. So, there are no bounds checking going on.