QML engine stops reporting reference errors

import QtQuick 2.15
import QtQuick.Window 2.15
import QtQuick.Controls 2.15

Window {
    visible: true

    // doesn't need to be an inline component, normal component also works
    component TestButton: Button {
        // when the following line exists no reference errors for the application will be reported
        background.opacity: 0.5
    }

    TestButton {
        // this property references something non-existing so it should cause a reference error
        property bool normallyCausesReferenceError: test

        background: Item {}
    }
}