QML inline components cannot reference inner objects

import QtQuick 2.15
import QtQuick.Window 2.15

Window {
    width: 200
    height: 100
    visible: true
    title: "Inline component test"

    component TestComponent : Item {
        property alias text: innerText.text

        width: innerText.implicitWidth
        height: innerText.implicitHeight

        Text {
            id: innerText
        }
    }

    TestComponent {
        text: "Something"
    }
}

qrc:/main.qml:25:9: Cannot assign to non-existent property "text"

qrc:/main.qml:15: ReferenceError: innerText is not defined
qrc:/main.qml:14: ReferenceError: innerText is not defined