Throw errors about scratch-js

[richgilbank]

A little slow to take a look at this, but I finally had a chance to see what was up here. It seems that getting raw access to the page's execution context via chrome.devtools.inspectedWindow.eval still catches errors that occur (https://developer.chrome.com/extensions/devtools_inspectedWindow#method-eval).

There are 2 approaches as I see it: the extension could keep doing what it's doing and just listen for exceptions which is easier and I've pushed a fix for now. The other option would be to allow the exceptions to actually throw using native browser behaviour by executing the script a different way, one which unfortunately sandboxes things so there's no access to page JS. I tried that out too: a3ca928.

Any thoughts on which way is better? Or alternatives?
/cc: @UltCombo in case you have any thoughts on this.

[UltCombo]

I believe it is fine as long as the errors are logged to the console. Getting nice stack traces are usually a complete pain though (regarding sourcemaps/etc), so I usually don't mind ugly stack traces.
Sorry, I don't have any strong feelings in this topic. =]

[richgilbank]

Fixed with fe5ced2