config: set default on missing default_context key

[simobasso]

Closes: #1514
Closes: #1149

[acturner]

EDIT: Fixed #1514 but not #1513 (the latter error coming from poyo).

For testing, you can clone cookiecutter-value-error and then run:

cookiecutter cookiecutter-value-error --config-file=cookiecutter-value-error/init.yaml --no-input

[simobasso]

@acturner thanks, just updated the description and also, I've found #1149 that seems the same issue.

[glumia]

lgtm!

The fact you had to update both tests/test_get_config.py::test_get_config and tests/test_get_user_config.py::custom_config after editing tests/test-config/valid-config.yaml is a clear sign of code duplication, we should have a single fixture as source of truth of file's content. @simobasso do you think it would be worth to open a refactor issue for that?

[simobasso]

Sure @glumia! Feel free to open an issue on this!