How to solve Gazebo error
Error [Param.cc:451] Unable to set value [-nan -nan -nan] for key[size] gzclient: /build/ogre-1.9-mqY1wq/ogre-1.9-1.9.0+dfsg1/OgreMain/src/OgreNode.cpp:630: virtual void Ogre::Node::setScale(const Ogre::Vector3&): Assertion `!inScale.isNaN() && "Invalid vector supplied as parameter"' failed. Aborted (core dumped) [gazebo_gui-2] process has died [pid 5196, exit code 134, cmd /opt/ros/kinetic/lib/gazebo_ros/gzclient __name:=gazebo_gui __log:=/home/parkkuyeon/.ros/log/3c4b6ea2-d439-11e9-a32f-c82158fbf97d/gazebo_gui-2.log]. log file: /home/parkkuyeon/.ros/log/3c4b6ea2-d439-11e9-a32f-c82158fbf97d/gazebo_gui-2*.log
Firstly you'll be better off posting this question on the Gazebo answers forum, this is not ROS related.
Secondly, you will not get much help if you just copy and paste an error message! We're happy to help, but if you don't tell us what you're trying to do, the commands/source files you've used, and describe exactly what happened, then we can't help you.