QML Canvas, reset line dash failed

import QtQuick 2.12
import QtQuick.Window 2.12

Window {
    width: 640
    height: 480
    visible: true

    Canvas {
        anchors.fill: parent
        onPaint: {
            var ctx = getContext("2d")
            ctx.lineWidth = 3

            ctx.save()
            ctx.setLineDash([3, 5])
            ctx.beginPath()
            ctx.moveTo(0, 0)
            ctx.lineTo(250, 250)
            ctx.stroke()
            ctx.restore()

            ctx.save()
            ctx.setLineDash([]) //no effect
            ctx.beginPath()
            ctx.moveTo(50, 0)
            ctx.lineTo(300, 250)
            ctx.stroke()
            ctx.restore()
        }
    }
}