Stricter settings flip

[mallyvai]

Django-waffle is awesome! Feature request - Looks like there are default values assigned for switches that aren't defined in the database yet. I'd love some settings to either/or:

1. Logging any switches/flags/etc that are attempted on read but undefined in the database
2. A setting that fails the request if the setting isn't retrievable

It's easy for feature-flags to sort of get strewn about the code, and this sort of thing can help enforce discipline / rigor with their implementation.

[jsocol]

Logging non-existent settings is a great idea! We can probably just log them to a waffle logger at a WARNING level and let folks configure/silence the logger if they want to.

[koliber]

Logging nonexistent flag checks is a valuable improvement. The PR would be tin, seemingly uncontentious, and easy to merge in.

Is there anything that needs to be done before such a PR can be made?

[bmoelans]

See #310 that solves logging issue, it is a change we already use as "fork" at our company

Main reasons:

• is more likely you add good description to it
• you can find in history who created that feature flipper and thus plausible can give you more details