fix: 修复自定义聊天bug

(cherry picked from commit 8d41c17ccf19cb29100dbe506d3d42a6be822ff9)

constant/chat.go

@@ -21,6 +21,7 @@ var Chats = []map[string]string{
 }
 
 func UpdateChatsByJsonString(jsonString string) error {
+	Chats = make([]map[string]string, 0)
 	return json.Unmarshal([]byte(jsonString), &Chats)
 }