InvalidOperationException: 集合已修改；可能无法执行枚举操作。
StackTrace:
   在 System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   在 System.Collections.Generic.Dictionary`2.Enumerator.MoveNext()
   在 Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeDictionary(JsonWriter writer, IDictionary values, JsonDictionaryContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   在 Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value, Type objectType)
   在 Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value, Type objectType)
   在 Newtonsoft.Json.JsonConvert.SerializeObjectInternal(Object value, Type type, JsonSerializer jsonSerializer)
   在 DynamicClass.TimingFunction.<>c__DisplayClass3.<.ctor>b__0(Object s, EventArgs e)
   在 System.Windows.Threading.DispatcherTimer.FireTick(Object unused)
   在 System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   在 System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)