I'm stuck trying to fix the errors in the testsuite. For starters, it seems to depend on the compiler version: I don't get those with Ubuntu's 20 compiler (9.x) but I do with 11.2. And then, when I run the test steps by hand, I don't get the exception either.

I guess something in the test environment is having something to do, but event trying to set up it by hand in advance is not working.

Glad for any ideas on what to try.

So after some trial and error, the only "simple" solution I could find was to manually manage and trigger the finalization of the new Configuration field in the Root record. Since this is functionally equivalent, I find it all very suspect.