This bug is the result of hovering over the wikilink [[October 23]] on en.wikipedia.org.
You need to have wikipedia's navigation popups installed in order to trigger the bug.
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Created attachment 13698 [details]
Doesn't crash on NB r20285
Thank you for checking with a nightly build! Closing per the above comment, as there isn't much we can do with a bug that's already fixed.
You can report this to vendors such as Apple (http://bugreport.apple.com) or Omni to request expedite integration into their respective releases.