What do I wait for to avoid RViz error "No robot state or robot model loaded" on launch?

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Including panda_control_moveit_rviz.launch in my own launch file which also launches a process which moves the robot results in

[ERROR] - [/rviz_<rviz_anonymized_name>::TrajectoryVisualization::incomingDisplayTrajectory::464]: No robot state or robot model loaded`.

This error is completely ignored and the process seems to run fine except for an update issue with the hand of the robot (possibly even unrelated).

Upon further investigation, this seems to stem from launch order, in the sense that running the other nodes separately beforehand and launching my own move-the-robot node after the others (rviz included) are initialized, avoids the message entirely.

Since roslaunch doesn't guarantee startup order I sought out to find which service/topic/other to wait on for before starting my own node, as I was doing in another case for planning scene service get_planning_scene, but:

• I wanted to add a breakpoint at the incomingDisplayTrajectory call with gdb but I couldn't find some package like ros-kinetic-rviz-dbg as per this to have debug symbols, so that didn't work;
• I couldn't find anything from exploring the RViz source code: I worked my way from the top to the likely path that leads to the message, found out it needs robot_loaded_ true in robot.h and from there went to RobotModelDisplay but in the end couldn't solve the issue.

In the end I would only like to find out what I should wait for, but it would be nice to know if the only way to set the breakpoint I wanted to would have been to get rviz from source and recompile it myself.

UPDATE 1:

UPDATE 2: I have both robot_state_ and robot_mndel_ empty...

Thread 1 "rviz" hit Breakpoint 1, moveit_rviz_plugin::TrajectoryVisualization::incomingDisplayTrajectory (this=0x1512de0, msg=...) at /home/ap/catkin_ws/src/moveit/moveit_ros/visualization/rviz_plugin_render_tools/src/trajectory_visualization.cpp:460
460     {
(gdb) s
[ERROR] - [/rviz_ap_NUC7i7DNKE_32236_8470600300558912922::PollSet::update::194]: poll failed with error Interrupted system call
[Thread 0x7fffd0d9c700 (LWP 2149) exited]
462       if (!robot_state_ || !robot_model_)
(gdb) display robot_state_
1: robot_state_ = std::shared_ptr<moveit::core::RobotState> (empty) = {get() = 0x0}
(gdb) display robot_model_
2: robot_model_ = std::shared_ptr<const moveit::core::RobotModel> (empty) = {get() = 0x0}
(gdb)

This, combined with the 5 calls printing "Loading robot model 'panda'..." is somewhat suspicious.