dbt debug cannot handle an empty dbt_project.yml

[nchammas]

Describe the bug

If you call dbt debug on a new project that has an empty dbt_project.yml file, you get this error:

Encountered an error:
'NoneType' object does not support item assignment

Steps To Reproduce

Create a new project directory and place an empty dbt_project.yml in it. Run dbt debug.

Expected behavior

dbt should gracefully complain that I have an empty or malformed dbt_project.yml.

Screenshots and log output

$ dbt debug
Running with dbt=0.15.2
dbt version: 0.15.2
python version: 3.7.6
python path: .../venv/bin/python
os info: Darwin-18.7.0-x86_64-i386-64bit
Using profiles.yml file at .../.dbt/profiles.yml

Encountered an error:
'NoneType' object does not support item assignment

System information

Which database are you using dbt with?

• postgres

The output of dbt --version:

$ dbt --version
installed version: 0.15.2
   latest version: 0.15.2

Up to date!

The operating system you're using: macOS

The output of python --version: Python 3.7.6

[drewbanin]

Thanks for the report @nchammas! Adding this to the current milestone. Would you be interested in contributing a fix for the issue? Happy to point you in the right direction if so!