add safety check

src/chat.rs

@@ -188,11 +188,12 @@ impl ChatDB {
                 }
             }
             for (index, label) in changes {
+                if index < vector.len() {
                     vector.remove(index);
                     vector.splice(index..index, include_db[&label].iter().cloned());
                 }
             }
-        return;
+        }
     }
 
     pub fn get_chat_by_id(&self, id: &String) -> Result<usize, String> {