https://github.com/kategengler/ember-cli-code-coverage/blob/ca8ffbb9f3f2864e21dc53bfa5241b1ad3941529/lib/attach-middleware.js#L22

Somehow the passed in fileLookup is null.

I did some investigation. include hook is indeed called before serverMiddleware, but the this.fileLookup in serverMiddleware is not the same instance as the one in include.

This is on ember-cli-code-coverage@1.0.0-beta.4