crash if not correct type

pkg/actor/mutation_registry.go

@@ -104,12 +104,17 @@ func NewMutation[V any, T proto.Message](handler func(*V, T) error) *RegisteredM
 	// This avoids relying on reflect.TypeFor (which can yield unexpected results in some toolchains)
 	// and ensures we always peel off the pointer layer for proto messages.
 	create := func() proto.Message {
-		m := new(T)
-		return *m
+		var t T
+		rt := reflect.TypeOf(t)
+		if rt != nil && rt.Kind() == reflect.Pointer {
+			return reflect.New(rt.Elem()).Interface().(proto.Message)
+		}
+		log.Fatalf("expected to create proto message got %+v", rt)
+		return nil
 	}
 	instance := create()
 	rt := reflect.TypeOf(instance)
-	if rt.Kind() == reflect.Ptr {
+	if rt.Kind() == reflect.Pointer {
 		rt = rt.Elem()
 	}
 	return &RegisteredMutation[V, T]{
@@ -222,7 +227,7 @@ func (r *ProtoMutationRegistry) Apply(ctx context.Context, grain any, msg ...pro
 		}
 		// Typed nil: interface holds concrete proto message type whose pointer value is nil.
 		rv := reflect.ValueOf(m)
-		if rv.Kind() == reflect.Ptr && rv.IsNil() {
+		if rv.Kind() == reflect.Pointer && rv.IsNil() {
 			continue
 		}
 		rt := indirectType(reflect.TypeOf(m))