ADDITIONAL SYSTEM INFORMATION :
Ubuntu 20.04, Java 17.0.1 (openjdk)

A DESCRIPTION OF THE PROBLEM :
When trying to compile a Java file with a nested switch expression (see the reproduce section), the Java compiler fails with a NullPointerException:
```
An exception has occurred in the compiler (17.0.1). 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: Cannot invoke "com.sun.tools.javac.code.Symbol.isEnum()" because "expr.sym" is null
```

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Invoke javac TestFile.java (the content of which is pasted in source code below)

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
No exceptions, a compiled Java file.
ACTUAL -
A Nullpointer exception:
An exception has occurred in the compiler (17.0.1). 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: Cannot invoke "com.sun.tools.javac.code.Symbol.isEnum()" because "expr.sym" is null

---------- BEGIN SOURCE ----------
public class EnumSwitchTestCase {
  enum Type {
    FIRST
  }

  enum Subtype {
    A,
    B
  }

  enum ResultType {
    ONE,
    TWO
  }

  interface Method {
    Type type();
  }

  record FirstMethod(Subtype subtype) implements Method {
    @Override
    public Type type() {
      return Type.FIRST;
    }
  }

  record Something(Method method) {}

  record Entity(ResultType resultType) {}

  public static void main(final String[] args) {
    final var something = new Something(new FirstMethod(Subtype.A));
    final Entity entity =
        new Entity(
            switch (something.method().type()) {
              case FIRST -> switch (((FirstMethod) something.method()).subtype()) {
                case A -> ResultType.ONE;
                case B -> ResultType.TWO;
              };
            });
    System.out.println(entity);
  }
}
---------- END SOURCE ----------

FREQUENCY : always