We've all been there at some point. Your app works great on your machine, all features are ready to be pushed to dev/acc, and when you do, all hell breaks loose.
Unknown provider: eProvider <- e
And you'll be like 'What eProvider, who put it there, where did that come from?' :). Don't worry, we've all been there at one point.
This problem will occur when the injector service is not able to retrieve an implementation that you requested in your module.