Hello ,
It seems like that UFont::GetMaxCharHeight() function is accessing something that turns out to be null and causes the crash but that doesn’t really tell us but so much. Are you able to get any logs from the packaged product? Also, please try playing in Standalone Window in the editor and/or trying to package for a different configuration such as Development or Shipping, whichever one you weren’t using. While doing these things, try quitting the same way to see if you crash there as well so we can see if it is only the packaged product and if it is specific to a particular configuration.