I have been reckless and updated to Mojave.
Actually my computer runs better now.
But one thing broke. And that was the scripting additions in AppleScript.
I only use Satimage. And only in KM with scripts from the excellent @ccstone.
To fix it I did as suggested in this forum:
It cleverly says not to rely to much on scripting additions in the future since Apple probably will break it some more.