Effect maker: Project with created effect cannot be started

When there is created effect in the project, it cannot be started with our QML player

Steps to reproduce

1. Create effect into the project
2. Apply effect to some 2D content
3. Try to launch it with 'play' icon

Expected result: Project runs and user can see the effect applied to an element

Actual behaviour: Project fails to start, output log gives this:

23:48:21: Starting /Users/jarkovihriala/Applications/QtDesignStudio-3.8.0-snapshot/qt6_design_studio_reduced_version/bin/qml -I /Users/jarkovihriala/UntitledProject1/imports -I /Users/jarkovihriala/UntitledProject1/asset_imports --apptype widget /Users/jarkovihriala/UntitledProject1/content/App.qml...
QQmlApplicationEngine failed to load component
file:///Users/jarkovihriala/UntitledProject1/content/App.qml:41:5: Type Screen01 unavailable
file:///Users/jarkovihriala/UntitledProject1/content/Screen01.ui.qml:64:5: MyEffect is not a type
qml: Did not load any objects, exiting.
23:48:23: /Users/jarkovihriala/Applications/QtDesignStudio-3.8.0-snapshot/qt6_design_studio_reduced_version/bin/qml exited with code 2