Error: invalid pipeline config

[MostHated]

Hey there,
This is my first day trying out concourse and I just happened upon this repo so I was quite excited to try it out, but unfortunately, upon giving it a go I got an error.

I followed the steps from concourse, I first started the docker-compose, then ran:

fly -t ci login -c http://127.0.0.1:8080 -u test -p test
fly -t ci set-pipeline -p app -c demo-pipeline.yml 

But unfortunately that gave me the following:

apply configuration? [yN]: y
error: invalid pipeline config:
invalid jobs:
        jobs.build.plan[2] has no action specified

Did I do something incorrectly? I was able to use a similar method for their initial demo which worked, so I don't think I missed anything.
Thanks,
-MH