Fixed possible nullpointer segfault

[werner291]

Fix for #94

[rhaschke]

I guess you are using this constructor:
https://github.com/ros-planning/moveit_visual_tools/blob/c166f8ee6412023b4183fc091abe6acbcdba2448/src/moveit_visual_tools.cpp#L79-L86

What about adding loadSharedRobotState() there - just like in the other constructor:
https://github.com/ros-planning/moveit_visual_tools/blob/c166f8ee6412023b4183fc091abe6acbcdba2448/src/moveit_visual_tools.cpp#L75-L76

[werner291]

That's up to the maintainers of this repo to decide... There's a bunch of lines of the form:

// Always load the robot state before using
loadSharedRobotState();

I figured there's a reason they do this rather than do it in the constructor, so I just copied that style.

[v4hn]

What about adding loadSharedRobotState() there - just like in the other constructor:

The other constructor was added quite recently as an interface for new users. The original interfaces by @davetcoleman were all designed to initialize the state lazily so I would keep it that way.

There are so much worse things to criticize about the VisualTools interfaces... 🗡️

I added more safeguards and cleaned up the format error.