修改网络连接断开时抛出exception的行为，可预知的异常就不打印error了

Unity/Assets/Scripts/Codes/Model/Share/Module/Message/Session.cs

@@ -114,7 +114,15 @@ namespace ET
             self.requestCallbacks[rpcId] = rpcInfo;
             request.RpcId = rpcId;
             self.Send(request);
-            return await rpcInfo.Tcs;
+
+            try
+            {
+                return await rpcInfo.Tcs;
+            }
+            catch(Exception)
+            {
+            }
+            return null;
         }
 
         public static void Send(this Session self, IMessage message)