From 913142f9c71a354f96ceddd9c3e78b054c8fc803 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juraj=20Or=C5=A1uli=C4=87?= <juraj.orsulic@fer.hr>
Date: Mon, 26 Mar 2018 13:47:15 +0000
Subject: [PATCH] Avoid failed CHECK when running offline node with no bags.
 (#777)

Bug introduced in #680.
---
 cartographer_ros/cartographer_ros/offline_node.cc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/cartographer_ros/cartographer_ros/offline_node.cc b/cartographer_ros/cartographer_ros/offline_node.cc
index 7709c50..e5f40e7 100644
--- a/cartographer_ros/cartographer_ros/offline_node.cc
+++ b/cartographer_ros/cartographer_ros/offline_node.cc
@@ -236,7 +236,11 @@ void RunOfflineNode(const MapBuilderFactory& map_builder_factory) {
 
   // TODO(gaschler): Warn if resolved topics are not in bags.
   std::unordered_map<int, int> bag_index_to_trajectory_id;
-  const ros::Time begin_time = playable_bag_multiplexer.PeekMessageTime();
+  const ros::Time begin_time =
+      // If no bags were loaded, we cannot peek the time of first message.
+      playable_bag_multiplexer.IsMessageAvailable()
+          ? playable_bag_multiplexer.PeekMessageTime()
+          : ros::Time();
   while (playable_bag_multiplexer.IsMessageAvailable()) {
     if (!::ros::ok()) {
       return;