catch exception from EVAL in MathJax.js

the function 

var EVAL = function(code){
   return eval.call(window, code);
}

throws an exception when the code is invalid. this may happen when the user makes something like 

<script type="text/javascript" src="http://cdn.mathjax.org/mathjax/latest/MathJax.js"><!----></script>

In my case this happens because the .CHM file compiler adds the <!---->, so i do not have control over this. 

I suggest to catch the exception and return a default value that does not cause problems.