How to understand why a Segmentation fault (core dumped) occurs?

Question

Node.js

I made a repository with an example, but for some reason, when using the sleep function, NodeJS crashes. I wrote to the developer, of course: https://github.com/jochemstoel/nodejs-system-sleep...
But I would like to understand why such errors occur, how to debug them in NodeJS and solve
Repo: https://github.com /splincode/recursive-phantomjs