REGRESSION: Warning "Unable to assign QString to QByteArray"

import QtQuick 2.0

ShaderEffect {
    id: root

    width: 100
    height: 100

    Timer {
        id: timer
        onTriggered: root.tick = !root.tick
        interval: 1000
        repeat: true
        running: true;
    }

    property bool tick
    onTickChanged: print("tick..")

    property variant source: ShaderEffectSource { }

    fragmentShader: tick ? '' : "void main() { gl_FragColor = vec4(1, 0, 0, 1); }"
}