handle dynamic json data and examples for subscription details

pkg/actor/mutation_registry.go

@@ -171,11 +171,21 @@ func (r *ProtoMutationRegistry) Apply(grain any, msg ...proto.Message) ([]ApplyR
 	if grain == nil {
 		return results, fmt.Errorf("nil grain")
 	}
+	// Nil slice of mutations still treated as an error (call contract violation).
 	if msg == nil {
 		return results, fmt.Errorf("nil mutation message")
 	}
 
 	for _, m := range msg {
+		// Ignore nil mutation elements (untyped or typed nil pointers) silently; they carry no data.
+		if m == nil {
+			continue
+		}
+		// Typed nil: interface holds concrete proto message type whose pointer value is nil.
+		rv := reflect.ValueOf(m)
+		if rv.Kind() == reflect.Ptr && rv.IsNil() {
+			continue
+		}
 		rt := indirectType(reflect.TypeOf(m))
 		r.mutationRegistryMu.RLock()
 		entry, ok := r.mutationRegistry[rt]
@@ -188,10 +198,6 @@ func (r *ProtoMutationRegistry) Apply(grain any, msg ...proto.Message) ([]ApplyR
 		results = append(results, ApplyResult{Error: err, Type: rt.Name(), Mutation: m})
 	}
 
-	// if entry.updateTotals {
-	// 	grain.UpdateTotals()
-	// }
-
 	return results, nil
 }