throw error if no pipeline

[jimsheldon]

[jimsheldon]

This should fix #14

[microadam]

Hi @jimsheldon. Thanks for the contribution. I am not sure this will work though, as this seems to assume that there will only be ONE yaml doc in the drone file. There could be multiple pipelines or even things like:

---
kind: secret

This PR assumes that it will only contain ONE yaml doc, so if you used a secret doc, it would break as you are throwing within a map function

[jimsheldon]

Thanks @microadam we will look into this

[jimsheldon]

@microadam I pushed a fix that should handle non-pipeline kinds properly

[microadam]

Thanks for this! I will try and have a proper look through this soon. I really need to get some unit tests on this project so we can ensure no existing functionality breaks with little changes like this.