Repository: ouster-lidar/ouster-ros (language: cpp)

Issue:
replay.launch crashes if you do not provide a value for the bag_file arg
**Describe the bug**
`roslaunch ouster_ros replay.launch` crashes if you do not provide a value for the `bag_file` argument. This is a problem if you want to play the rosbag and launch `replay.launch` in separate terminals. 

**To Reproduce**
Steps to reproduce the behavior (steps below are just an example):
1. Build the ouster_ros package
2. `roslaunch ouster_ros replay.launch`

**Platform (please complete the following information):**
- ROS version/distro: noetic
- Operating System: Linux
- Machine Architecture: x64, arm
- git commit hash 1dbdbb4317fa8f38ffb442513f889e379fe125ab



Discussion / hints:

Fix patch:
diff --git a/launch/replay.launch b/launch/replay.launch
index 0c66c3fb..a970b916 100644
--- a/launch/replay.launch
+++ b/launch/replay.launch
@@ -15,7 +15,7 @@
 
   <arg name="ouster_ns" default="ouster" doc="Override the default namespace of all ouster nodes"/>
   <arg name="metadata" default="" doc="path to read metadata file when replaying sensor data"/>
-  <arg name="bag_file" doc="file name to use for the recorded bag file"/>
+  <arg name="bag_file" default="" doc="file name to use for the recorded bag file"/>
   <arg name="timestamp_mode" default="TIME_FROM_INTERNAL_OSC"
     doc="A parameter that allows you to override the timestamp measurements; possible values: {
     TIME_FROM_INTERNAL_OSC,


Test patch: