rare ansible error: failed to combine variables, expected dicts but got a 'dict' and a 'list'

[sam]

Hi, I am receiving an error that isn't shown anywhere in my search results:

"ERROR: failed to combine variables, expected dicts but got a 'dict' and a 'list'"

Here's the error in its entirety:

https://gist.github.com/uunsamp/3d484b1c4a70ca871e9d

Here's all the related files: 

  https://gist.github.com/uunsamp/5371b811d7f2758d80ff

I've even tried configuring the hosts file to look like this:

https://gist.github.com/uunsamp/cbf35a92e2070c4a4924

Any kind of help would be appreciated, I actually had vagrant and ansible working yesterday, but I deleted all of that work :|

[sam]

 I figured it out, I had vars/main.yml and tasks/main.yml for one of my roles mixed up! i.e. I put tasks in vars/main.yml and vars in tasks/main.yml