Illegal access Javascript error in Chrome

Question

I have sporadically been getting an "illegal access" exception in Chrome (29 and 30). Others have also seen this. It seems to happen on one specific line:

Here, this is an object I defined. It has a property end which is null or a number.

Does anyone know of anything that could cause an error with that message in Chrome?

EDIT: I don't expect anyone to debug ten thousands of lines of my code. What could cause an error with that message, whether it be jumping off the moon, singing blues, etc?

There are no occurrences of "illegal" in all of the Javascript code on the page.

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This error has not happened in later versions of Chrome (31+).

Hopefully this is gone for good.

Answer 1

According to https://github.com/highcharts/highcharts/issues/2443, this would help:

try {
   delete ret['e'];
} catch (e) {} // do nothing