Make y2020 multinode!

Update the configs.  It all starts on a roboRIO, and forwards RobotState
between nodes.  Need to finalize deployment for pi's.

Change-Id: I2601419a94ca154e9663c916e9b8987d73ffa814
diff --git a/aos/events/logging/logfile_utils.cc b/aos/events/logging/logfile_utils.cc
index 44381f3..f062ad3 100644
--- a/aos/events/logging/logfile_utils.cc
+++ b/aos/events/logging/logfile_utils.cc
@@ -1048,6 +1048,12 @@
 
 TimestampMerger::DeliveryTimestamp ChannelMerger::OldestTimestampForChannel(
     int channel) const {
+  // If we didn't find any data for this node, we won't have any mergers. Return
+  // an invalid timestamp in that case.
+  if (timestamp_mergers_.size() <= static_cast<size_t>(channel)) {
+    TimestampMerger::DeliveryTimestamp result;
+    return result;
+  }
   return timestamp_mergers_[channel].OldestTimestamp();
 }