Program crash when assigning a value to transition property

 
import QtQuick 1.0

Rectangle {
    id: canvas
    height: 500; width: 600

    Rectangle { id: rect; color: "blue"; height: 100; width: 100 }

    state: "A"
    states: [
        State { name: "A"; PropertyChanges { target: rect; x: 0; y: 100 } },
        State { name: "B"; PropertyChanges { target: rect; x: 500; y: 100 } }
    ]

    property list<Transition> trans1: [
        Transition {
            NumberAnimation { target: rect; property: "x"; duration: 500 }
        }
    ]
    transitions: trans1

    Timer { interval: 1000; running: true; onTriggered: canvas.state = "B" }
    Timer { interval: 2000; running: true; onTriggered: canvas.state = "A" }
}