Improve oversized send error on SimulatedEventLoop

We were reporting how much bigger it was, but not reporting the
channel.

Change-Id: Ia57a7fcf3cca30f355dbad8e6baa2fdc505d174b
diff --git a/aos/events/simulated_event_loop.cc b/aos/events/simulated_event_loop.cc
index 4c28039..9c8bb09 100644
--- a/aos/events/simulated_event_loop.cc
+++ b/aos/events/simulated_event_loop.cc
@@ -856,7 +856,9 @@
     aos::monotonic_clock::time_point monotonic_remote_time,
     aos::realtime_clock::time_point realtime_remote_time,
     uint32_t remote_queue_index) {
-  CHECK_LE(size, this->size()) << ": Attempting to send too big a message.";
+  CHECK_LE(size, this->size())
+      << ": Attempting to send too big a message on "
+      << configuration::CleanedChannelToString(simulated_channel_->channel());
 
   // This is wasteful, but since flatbuffers fill from the back end of the
   // queue, we need it to be full sized.