avoid crash when chat "include" label doesn't exist

src/chat.rs

@@ -190,7 +190,9 @@ impl ChatDB {
             for (index, label) in changes {
                 if index < vector.len() {
                     vector.remove(index);
-                    vector.splice(index..index, include_db[&label].iter().cloned());
+                    if let Some(chat) = include_db.get(&label) {
+                        vector.splice(index..index, chat.iter().cloned());
+                    }
                 }
             }
         }