I'm getting the an error of "Failed to fetch stories"

The console error is: (index):464 Error loading stories: TypeError: Failed to construct 'URL': Invalid URL at (index):482:36 at Array.forEach (<anonymous>) at NewspaperApp.displayStories ((index):471:25) at NewspaperApp.loadStories ((index):461:26) at async NewspaperApp.initialize ((index):418:17)

Can anyone help? I really want to use this product it seems great.