Python kernal crashing

I am using Spyder with python 3.7. As soon as I run my code the kernal crashes.

The following is my sample code:

import pybulletgym
import gym
env_name = 'HumanoidPyBulletEnv-v0'
env = gym.make(env_name)

env.render()
env.reset()

for i in range(10000):
 obs, rewards, done, _ = env.step(env.action_space.sample())
env.close()


What could be reason for the crash?
