Al componente le falta una propiedad obligatoria

import QtQuick

Item {
    component RepeatMe: Item {
        required property int index;
        required property int helloWorld;
    }

    RepeatMe {} // not ok: required properties index and helloWorld not set

    Repeater {
        model: 10
        RepeatMe {} // not ok: required property index set by Repeater, but not helloWorld
    }
}

import QtQuick

Item {
    component RepeatMe: Item {
        required property int index;
        required property int helloWorld;
    }

    RepeatMe {
        index: 0
        helloWorld: 42
    } // ok: all required properties were set

    Repeater {
        model: 10
        RepeatMe {
            helloWorld: index * 2 + 1
        } // ok: all required properties were set: index by the Repeater and helloWorld by the user
    }
}