String freeze exception for Plasma 6.8 in libplasma

[Marco Martin]

Hi all,

we have the following merge request:
https://invent.kde.org/plasma/libplasma/-/merge_requests/1610

It introduces an error message dialog on a very rare occasion of wrong
plasma setup (99.999% of users should never see this).

We would like to have it in the 6.8 branch as well because we are
receiving on Sentry several crashes that suggest this situation, but
we don't know much more.
with this it wouldn't crash anymore and let the users experiencing
this report a bug with more useful descriptions of it.

-- 
Marco Martin