GPOS error on exporting variable font

On trying to export a variable font, I’m getting this error:
I found this forum thread and tried the Use Extension Kerning parameter, but it didn’t help. And this really shouldn’t be happening anyway, because the file doesn’t contain a lot of kerning yet!

Am running 3.0.4 (3099), but this happened with an earlier version too. The source is a big *.glyphspackage, which can be accessed here (it’s the italic).

Thanks for the report. I fixed it.

Thanks, Georg! I’ll look forward to the update.