为啥使用canvas绘制完成后会出现黑色边框
代码：
<canvas type="2d" id="canvasChessBoard"></canvas>
const query = wx.createSelectorQuery()
query.select('#canvasChessBoard')
.fields({ node: true, size: true })
.exec((res) => {
const canvas = res[0].node
const ctx = canvas.getContext('2d')
// ctx.drawImage(dataTemp.strPathImgChessboard, 0, 0, dataTemp.nCanvChessBoardWidth, dataTemp.nCanvChessBoardHeight)
const dpr = wx.getSystemInfoSync().pixelRatio
canvas.width = res[0].width * dpr
canvas.height = res[0].height * dpr
ctx.scale(dpr, dpr)
ctx.fillRect(0, 0, 100, 100)
})
请具体描述问题出现的流程，并提供能复现问题的简单代码片段（https://developers.weixin.qq.com/miniprogram/dev/devtools/minicode.html）。
<canvas type="2d" id="canvasChessBoard"></canvas>const query = wx.createSelectorQuery()query.select('#canvasChessBoard').fields({ node: true, size: true }).exec((res) => {const canvas = res[0].nodeconst ctx = canvas.getContext('2d')// ctx.drawImage(dataTemp.strPathImgChessboard, 0, 0, dataTemp.nCanvChessBoardWidth, dataTemp.nCanvChessBoardHeight)const dpr = wx.getSystemInfoSync().pixelRatiocanvas.width = res[0].width * dprcanvas.height = res[0].height * dprctx.scale(dpr, dpr)ctx.fillRect(0, 0, 100, 100)})解决了吗？是偶发还是100%复现？
@官方