Hector Quadcopter sim not working

When I try to initialize the gazebo sim of Hecto Quadcopter sim it does not show the quadcopter with its rotors. it show me this.

from Google Alert - quadcopter http://j.mp/2MM4wQN
via Tommy Gerlado

https://www.tommygerlado.com/2019/02/hector-quadcopter-sim-not-working.html