Qt Quick can't load SVG images without the Qt Widgets module

I'm displaying SVG images in my Qt Quick applications, however, they can't be loaded without the Qt Widgets module (Qt5Widgets.dll).

I don't understand why the widgets module is necessary to display a SVG image.

Minimum re-produce project attached.

Steps to reproduce:

1. Build the project.
2. Run the application and the SVG image can be displayed successfully
3. Delete or rename Qt5Widgets(d).dll
4. Re-open the application and the SVG image can't be loaded.