Provide helpful error when no keys are generated

[michaelwheeler]

I have observed, during my own development and when helping others, that people frequently forget to create a Key and receive a confusing Key matching query does not exist message.

Could we provide better guidance or a smoother path here? A few ideas:

• Provide a more helpful error message
• Automatically create a key as needed in DEBUG mode
• Add a system check when not in DEBUG mode