Stop completion when exception has occurred.

Author: Oceania2018

src/Infrastructure/BotSharp.Core/Conversations/Services/ConversationService.CallFunctions.cs

@@ -43,6 +43,7 @@ public async Task CallFunctions(RoleDialogModel msg)
             catch (Exception ex)
             {
                 msg.Content = ex.Message;
+                msg.StopCompletion = true;
                 _logger.LogError(msg.Content);
             }
 

src/Infrastructure/BotSharp.Core/Instructs/InstructService.CallFunctions.cs

@@ -37,6 +37,7 @@ private async Task CallFunctions(RoleDialogModel msg)
             catch (Exception ex)
             {
                 msg.Content = ex.Message;
+                msg.StopCompletion = true;
                 _logger.LogError(msg.Content);
             }