Ensure ObjectSpace.dump won't call cc_cme on invalidated CC

Author: jhawthorn

ext/objspace/objspace_dump.c

@@ -451,13 +451,16 @@ dump_object(VALUE obj, struct dump_config *dc)
             break;
 
           case imemo_callcache:
-            mid = vm_cc_cme((const struct rb_callcache *)obj)->called_id;
-            if (mid != 0) {
-                dump_append(dc, ", \"called_id\":");
-                dump_append_id(dc, mid);
-
+            {
                 VALUE klass = ((const struct rb_callcache *)obj)->klass;
-                if (klass != 0) {
+                if (klass != Qundef) {
+                    mid = vm_cc_cme((const struct rb_callcache *)obj)->called_id;
+                    if (mid != 0) {
+                        dump_append(dc, ", \"called_id\":");
+                        dump_append_id(dc, mid);
+
+                    }
+
                     dump_append(dc, ", \"receiver_class\":");
                     dump_append_ref(dc, klass);
                 }