JDK 22 introduced Unnamed Variables & Patterns. Currently, unnamed pattern variables do not seem to be supported in CFG construction. Test case from uber/NullAway#1168:

package org.example;

public class NullAwayDiscardError {

	public sealed interface IntOrBool {}
	public record WrappedInt(int a) implements IntOrBool {}
	public record WrappedBoolean(boolean b) implements IntOrBool {}

	public static void unwrap(IntOrBool i) {
		switch(i) {
			case WrappedInt(_) -> {}
			case WrappedBoolean(_) -> {}
		}
	}

}

This causes NullAway to crash. I think the reason is that WrappedInt(_) is represented as a DeconstructedPatternNode, but the nested pattern ends up as null. Here is the relevant code:

Here when we scan the nested pattern tree, it's an AnyPatternTree, which is not handled in CFG construction, so scan returns null. Other code does not expect a null nested pattern in a DeconstructedPatternNode leading to the crash.