port occupied detection

frontend/src/_locales/zh-hans/main.json

@@ -261,5 +261,6 @@
   "The content of file": "文件",
   "is as follows. When replying to me, consider the file content and respond accordingly:": "内容如下。回复时考虑文件内容并做出相应回复:",
   "What's the file name": "文件名是什么",
-  "The file name is: ": "文件名是："
+  "The file name is: ": "文件名是：",
+  "Port is occupied. Change it in Configs page or close the program that occupies the port.": "端口被占用。请在配置页面更改端口，或关闭占用端口的程序"
 }