Add a couple sanity-CHECK's in log_writer

Change-Id: I1681d1ba112821bcd2d1cc9f076492ac0c6070e9
Signed-off-by: James Kuszmaul <jabukuszmaul+collab@gmail.com>
diff --git a/aos/events/logging/log_writer.cc b/aos/events/logging/log_writer.cc
index 4e34b61..f379ca4 100644
--- a/aos/events/logging/log_writer.cc
+++ b/aos/events/logging/log_writer.cc
@@ -410,6 +410,7 @@
   } else if (server_statistics_fetcher_.get() != nullptr) {
     // We must be a remote node now.  Look for the connection and see if it is
     // connected.
+    CHECK(server_statistics_fetcher_->has_connections());
 
     for (const message_bridge::ServerConnection *connection :
          *server_statistics_fetcher_->connections()) {
@@ -430,6 +431,7 @@
         break;
       }
 
+      CHECK(connection->has_boot_uuid());
       const UUID boot_uuid =
           UUID::FromString(connection->boot_uuid()->string_view());