Fix error when creating MUC

Fixes #9473
5 jobs from master in 5 minutes and 8 seconds (queued for 7 seconds)
Status Job ID Name Coverage
  Test
passed #8826
run-appdata

00:00:06

passed #8824
run-mypy

00:00:27

passed #8825
run-pylint

00:03:43

passed #8823
run-test

00:00:38

 
  Build
passed #8827
run-build

00:00:12