StackMapTable is invalid if frames appear in dead code

If a class contains dead code, and if the dead code contains stack map frames, the written attribute ends up invalid, causing a class format error.

A reproducer:

 ClassFile classFile = ClassFile.of(ClassFile.StackMapsOption.DROP_STACK_MAPS);
    byte[] bytes = classFile.build(ClassDesc.of("foo.Bar"), classBuilder -> classBuilder.withMethod(
            "foo",
            MethodTypeDesc.ofDescriptor("()J"),
            0,
            methodBuilder -> {
                methodBuilder.withCode(codeBuilder -> {
                    codeBuilder.new_(ClassDesc.of(RuntimeException.class.getName()));
                    codeBuilder.dup();
                    codeBuilder.invokespecial(ClassDesc.of(RuntimeException.class.getName()),
                            "<init>",
                            MethodTypeDesc.ofDescriptor("()V"));
                    codeBuilder.athrow();
                    Label f2 = codeBuilder.newBoundLabel();
                    codeBuilder.lstore(1);
                    Label f3 = codeBuilder.newBoundLabel();
                    codeBuilder.lload(1);
                    codeBuilder.lreturn();
                    codeBuilder.with(StackMapTableAttribute.of(List.of(
                            StackMapFrameInfo.of(f2,
                                    List.of(StackMapFrameInfo.ObjectVerificationTypeInfo.of(ClassDesc.of("foo.Bar"))),
                                    List.of(StackMapFrameInfo.SimpleVerificationTypeInfo.ITEM_LONG)),
                            StackMapFrameInfo.of(f3,
                                    List.of(StackMapFrameInfo.ObjectVerificationTypeInfo.of(ClassDesc.of("foo.Bar")),
                                            StackMapFrameInfo.SimpleVerificationTypeInfo.ITEM_LONG),
                                    List.of())
                    )));
                });
            }));
    new ClassLoader() {
        @Override
        protected Class<?> findClass(String name) throws ClassNotFoundException {
            if (name.equals("foo.Bar")) {
                return defineClass(name, bytes, 0, bytes.length);
            } else {
                return super.findClass(name);
            }
        }
    }.findClass("foo.Bar").getMethods();