cabana: add empty check before insert events (#29798)

tools/cabana/streams/abstractstream.cc

@@ -167,8 +167,10 @@ void AbstractStream::mergeEvents(std::vector<Event *>::const_iterator first, std
     e.insert(insert_pos, new_e.cbegin(), new_e.cend());
   }
 
-  auto insert_pos = std::upper_bound(all_events_.cbegin(), all_events_.cend(), new_events.front(), compare);
-  all_events_.insert(insert_pos, new_events.cbegin(), new_events.cend());
+  if (!new_events.empty()) {
+    auto insert_pos = std::upper_bound(all_events_.cbegin(), all_events_.cend(), new_events.front(), compare);
+    all_events_.insert(insert_pos, new_events.cbegin(), new_events.cend());
+  }
 
   lastest_event_ts = all_events_.empty() ? 0 : all_events_.back()->mono_time;
   emit eventsMerged();