8281771: Crash in java_lang_invoke_MethodType::print_signature

Backport-of: a24498b777b76c04d7e6da0a8b5fb501f2fb4944

src/hotspot/share/classfile/javaClasses.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -4087,11 +4087,20 @@ void java_lang_invoke_MethodType::serialize_offsets(SerializeClosure* f) {
 void java_lang_invoke_MethodType::print_signature(oop mt, outputStream* st) {
   st->print("(");
   objArrayOop pts = ptypes(mt);
-  for (int i = 0, limit = pts->length(); i < limit; i++) {
-    java_lang_Class::print_signature(pts->obj_at(i), st);
+  if (pts != NULL) {
+    for (int i = 0, limit = pts->length(); i < limit; i++) {
+      java_lang_Class::print_signature(pts->obj_at(i), st);
+    }
+  } else {
+    st->print("NULL");
   }
   st->print(")");
-  java_lang_Class::print_signature(rtype(mt), st);
+  oop rt = rtype(mt);
+  if (rt != NULL) {
+    java_lang_Class::print_signature(rt, st);
+  } else {
+    st->print("NULL");
+  }
 }
 
 Symbol* java_lang_invoke_MethodType::as_signature(oop mt, bool intern_if_not_found) {