My colleague Alan Malloy discovered the following crash, which involves a circular enum declaration and annotation processing enabled:

=== EmptyProcessor.java
import java.util.Set;
import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.RoundEnvironment;
import javax.lang.model.element.TypeElement;

public class EmptyProcessor extends AbstractProcessor {
  @Override
  public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
    return false;
  }
}
=== Mistake.java
public enum Mistake implements Mistake {
  MISTAKE;
}
===

$ javac -fullversion
javac full version "13-ea+22"
$ javac EmptyProcessor.java
$ javac -processor EmptyProcessor Mistake.java
An exception has occurred in the compiler (13-ea). Please file a bug against the Java compiler via the Java bug reporting page (http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com) for duplicates. Include your program, the following diagnostic, and the parameters passed to the Java compiler in your report. Thank you.
java.lang.NullPointerException
at jdk.compiler/com.sun.tools.javac.comp.Attr.attribIdentAsEnumType(Attr.java:927)
at jdk.compiler/com.sun.tools.javac.comp.MemberEnter.visitVarDef(MemberEnter.java:263)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:962)
at jdk.compiler/com.sun.tools.javac.comp.MemberEnter.memberEnter(MemberEnter.java:163)
at jdk.compiler/com.sun.tools.javac.comp.MemberEnter.memberEnter(MemberEnter.java:175)