[KSP2] "PSI has changed since creation" in SymbolProcessor::finish

[kuanyingchou]

I saw this in XProcessing's XTypeTest.wildcardWithMissingType and this could be more of a feature request.

In XProcessing we run a pseudo last run when SymbolProcessor::finish is called here and may still try to access types and annotations in finish. But we're hitting PSI has changed since creation. Could it be that things are cleaned up here?

If it is since there're no new files generated and the caches are still valid is it possible to delay the clean up in the last round so that we won't hit this error in onError or finish? For example, if there're two rounds, instead of:

round 1
clean up
round 2 (final round)
clean up
onError or finish

we do:

round 1
clean up
round 2 (final round)
onError or finish
clean up

This one looks similar to #1854.