I was working through the 'Lightning Web Components Basics' trailhead unit and was successfully able to push the E-bikes demo app and components to my organization. As per the trailhead instructions, I was using the salesforce CLI command:

sfdx force:source:deploy -p force-app -u <username>

This worked initially, but after making the prescribed changes to some web components for the unit, the deploy command now fails with the error: 

The component must implement at least one of lightning__AppPage interface.

Even if I checkout the e-bike demo app code clean from GitHub, it still fails with the same error.
Is there something wrong with my CLI configuration? Or organization configuration?
 

I was working through the 'Lightning Web Components Basics' trailhead unit and was successfully able to push the E-bikes demo app and components to my organization. As per the trailhead instructions, I was using the salesforce CLI command:

sfdx force:source:deploy -p force-app -u <username>

This worked initially, but after making the prescribed changes to some web components for the unit, the deploy command now fails with the error: 

The component must implement at least one of lightning__AppPage interface.

Even if I checkout the e-bike demo app code clean from GitHub, it still fails with the same error.
Is there something wrong with my CLI configuration? Or organization configuration?