The add-on requires permission to access only relevant Github pages, but it's only evaluating the URLs and determining whether or not to redirect to the same URL with "w=1" appended. It is <b>not</b> reading any content.
At the moment, viewing diffs when comparing two branches does not force ignoring whitespace differences, because the entire browser hangs and CPU spikes to 100%. It has something to do with a specific URL structure (".../compare....user:branch") but I have yet to figure out what sort of regex would not cause Firefox to stall.
It does not seem to be related to the extension's code, because in that case the listener doesn't fire at all.
It does not seem to be related to the extension's code, because in that case the listener doesn't fire at all.