missing Fallback on PReferenceType.__new__

Author: cosminbasca

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/WeakRefModuleBuiltins.java

@@ -49,6 +49,8 @@
 import com.oracle.graal.python.builtins.objects.object.PythonObject;
 import com.oracle.graal.python.builtins.objects.referencetype.PReferenceType;
 import com.oracle.graal.python.nodes.function.PythonBuiltinNode;
+import com.oracle.graal.python.runtime.exception.PythonErrorType;
+import com.oracle.truffle.api.dsl.Fallback;
 import com.oracle.truffle.api.dsl.GenerateNodeFactory;
 import com.oracle.truffle.api.dsl.NodeFactory;
 import com.oracle.truffle.api.dsl.Specialization;
@@ -75,6 +77,11 @@ public PReferenceType refType(Object cls, PythonObject pythonObject, PNone none)
         public PReferenceType refType(Object cls, PythonObject pythonObject, PFunction callback) {
             return factory().createReferenceType(pythonObject, callback);
         }
+
+        @Fallback
+        public PReferenceType refType(@SuppressWarnings("unused") Object cls, @SuppressWarnings("unused")  Object object, @SuppressWarnings("unused") Object callback) {
+            throw raise(PythonErrorType.TypeError, "cannot create weak reference to '%p' object", object);
+        }
     }
 
     // getweakrefcount(obj)