I'm creating an app written in QML using Qt Creator 8.0.1

When I run the app with no custom components, everything goes well. No errors, but when I create a custom component and try to preview it in the Deisng Tab, it throws an error (Below, I leave imgur links since the attach function of this website doesnt work for me)
https://imgur.com/a/HNZGuHe

What's weird is that if I build the app, the thing works fine. But if I try to preview it in Qt Creator, boom, doenst work.