Random code corruption/errors

Hi

All of a sudden I'm getting random code corruption/errors such as this:

Uncaught Error: Field or method does not already exist, and can't create it on undefined
 at line 1 col 64
...deAt(1)+a.charCodeAt(2),w:a.charCodeBt(3),h:a.charCodeAt(4),..

As can be seen one of the charCodeAt statements has become charCodeBt !!!

Another example:

 at line 1 col 26
{return{x:a.charCodeAt(0+,y:a.charCodeAt(1)+a.charCodeAt(2),...

The closing bracket has become a + symbol.

Maybe its just how the error is being displayed but I don't think so.

I happen to remember someone else having similar issues - was there ever a solution?