fix: check if model returned at least 1 feedback

i18n/en.json

@@ -53,7 +53,8 @@
     "description": "The AI will ask you some follow up questions to help you clarify the research direction.",
     "waiting": "Waiting for model feedback...",
     "submit": "Submit Answer",
-    "error": "Error getting feedback: {0}"
+    "error": "Error getting feedback: {0}",
+    "noQuestions": "The AI model did not return any follow-up questions."
   },
   "webBrowsing": {
     "title": "3. Web Browsing",

i18n/zh.json

@@ -55,6 +55,7 @@
     "description": "AI 将会跟你确认一些细节，帮助你明确研究方向。",
     "waiting": "等待模型反馈...",
     "submit": "提交回答",
+    "noQuestions": "模型没有返回任何问题，请重试",
     "error": "获取反馈失败：{0}"
   },
   "webBrowsing": {