Add the failing channel to checking for has_timestamp_logger_nodes

We were exploding with nothing useful in the error.  Add the offending
channel to the error to aid debugging.

Change-Id: I01ad6efec1b83ce7d020e136b5bc2600119f6e1a
Signed-off-by: Austin Schuh <austin.schuh@bluerivertech.com>
diff --git a/aos/configuration.cc b/aos/configuration.cc
index 736f772..8bbbdd5 100644
--- a/aos/configuration.cc
+++ b/aos/configuration.cc
@@ -439,7 +439,8 @@
           switch (connection->timestamp_logger()) {
             case LoggerConfig::LOCAL_LOGGER:
             case LoggerConfig::NOT_LOGGED:
-              CHECK(!connection->has_timestamp_logger_nodes());
+              CHECK(!connection->has_timestamp_logger_nodes())
+                  << ": " << CleanedChannelToString(c);
               break;
             case LoggerConfig::REMOTE_LOGGER:
             case LoggerConfig::LOCAL_AND_REMOTE_LOGGER: