Please display error messages only when user tries to do something that is impossible. Not just random error message at program startup.
Created attachment 121757 [details] Screenshot_20190726_231504.png
That looks like a setup error. Which distribution are you using?
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Ubuntu 19.10
The editor was run as root without appropriate environment. If the program can't work without certain environment: better fail the startup with appropriate error message which gives direct understanding of how to fix.
After this error message program doesn't exit and continues to run in non-usable state.
Kate doesn't support running as root. You should still be able to edit root-owned files using its KAuth feature.
So print the appropriate error message and exit kate. What do you mean "not a bug" when Kate prints some cryptic error and continues to run in non-working state. This is not a bug for you, Christoph?????? I'm tired of your half-working software!!! Please, try to make it a little bit more user-friendly, so users wouldn't spend time by scratching their heads and deciphering what is going on with your programs!!!!
When I run 'sudo kate' there is a very clear message that reads "Executing Kate with sudo is not possible due to unfixable security vulnerabilities." and Kate aborts.