Glyphs sets `date` field in Arabic in Arabic locale, crashes when viewing a glyph

I set my system’s locale to Arabic and rebooted the Mac. When saving a file, Glyphs writes the date using an Arabic format. Opening such such a file works, but no glyphs are shown and opening the edit view crashes Glyphs. If I save the file with the edit view open (which opens the edit view directly when opening the file), Glyphs crashes immediately when opening such a file.

The following movie demonstrates this:

Directors commentary:

  • Act one: The locale is macOS standard Arabic.
  • I launch Glyphs and create a new file with ⌘N.
  • I save the file without editing it as Test.glyphs.
  • I close the window and quit Glyphs. (⌘W ⌘Q)
  • I open the file in TextMate; the date format does not match the spec.
  • I open the file in Glyphs; an empty list of glyphs is shown.
  • I quit Glyphs again and delete the file, end of act one.
  • Act two: I launch Glyphs and create a new file, but this time I save it with the edit view open.
  • I close the window and quit Glyphs.
  • I open the file; Glyphs launches and crashes without ever showing a window.
  • The crash report is presented by the system, end of act two.

I have uploaded the crash report (and also send it with the standard Glyphs crash reporter, after the movie ended), the second test-file is here:
Test.glyphs (5.8 KB)