KRunner now shows error messages for the Actions dbus request.
But they get only shown if the service is not unknown, because the same error message will be shown in the match method.

Make sure that the logging category is enabled and verify that you get debug output when starting KRunner.
Create a runner for example https://cgit.kde.org/scratch/davidedmundson/pythonrunner.git/tree/runner.py and install it.
Make sure that the Actions method is valid and returns actions, they should be displayed without warnings.
Change the return value from a list to 123, a TypeError message should be displayed.
Kill the runner, and type one letter in KRunner. The ServiceUnknown error message gets shown only once (from the match method).