ensure T_OBJECT objects have internals initialized

gc.c

@@ -2304,8 +2304,12 @@ rb_newobj(void)
 VALUE
 rb_newobj_of(VALUE klass, VALUE flags)
 {
+    if ((flags & RUBY_T_MASK) == T_OBJECT) {
+        return newobj_of(klass, (flags | ROBJECT_EMBED) & ~FL_WB_PROTECTED , Qundef, Qundef, Qundef, flags & FL_WB_PROTECTED);
+    } else {
         return newobj_of(klass, flags & ~FL_WB_PROTECTED, 0, 0, 0, flags & FL_WB_PROTECTED);
     }
+}
 
 #define UNEXPECTED_NODE(func) \
     rb_bug(#func"(): GC does not handle T_NODE 0x%x(%p) 0x%"PRIxVALUE, \