无法获取到canvas的context; js: wx.createSelectorQuery().select("#cutCanvas").context(function (res){var y = res.context;} wxml: <canvas canvas-id="cutCanvas" id="cutCanvas"  hidden="{{canvasHidden}}"     style="width:{{cutCanvasWH}}px; height: {{cutCanvasWH}}px;  "></canvas> 设备类型：Mi 10arm64-v8a，GLK-AL00arm64-v8a，JEF-AN00arm64-v8a，PCEM00arm64-v8a