fix for assistant response warning message.

Author: ashishrp-aws

packages/core/src/codewhispererChat/storages/chatHistory.ts

@@ -80,8 +80,9 @@ export class ChatHistoryManager {
      * Push an assistant message to the history
      */
     public pushAssistantMessage(newMessage: ChatMessage): void {
-        if (newMessage !== undefined && this.lastUserMessage !== undefined) {
-            this.logger.warn('last Message should not be defined when pushing an assistant message')
+        if (newMessage !== undefined && this.lastUserMessage === undefined) {
+            this.logger.warn('Assistant response should always come after user input message')
+            return
         }
         // check if last message in histroy is assistant message and now replace it in that case
         if (this.history.length > 0 && this.history.at(-1)?.assistantResponseMessage) {