downloadFile下载之后，是wxfile://tmp_bdaba1387d3980577cccc623fd6bcf3d96156d38b033aea8.jpg 然后再使用drawImage合成图片之后，在模拟器上是好的，在真机上就是一张空白图片？

在开发者工具中没问题，上传至体验版后用手机访问无法显示页面 开发过程中使用了vant组件 thirdScriptError TypeError: Cannot read property 'getElementsByTagName' of undefined TypeError: Cannot read property 'getElementsByTagName' of undefined at at (app-service.js:5770:6757) at at (app-service.js:5770:7967) at require (WASubContext.js:2:1679381) at at (app-service.js:5771:10) appServiceSDKScriptError SubContext evaluateScriptFile "app-service.js" failed: error code 0;at wxConfig.onReady callback Error: SubContext evaluateScriptFile "app-service.js" failed: error code 0 at s.value (WAServiceMainContext.js:2:144031) at WAServiceMainContext.js:2:146440 at Array.forEach (<anonymous>) at WAServiceMainContext.js:2:146418 at h (WAServiceMainContext.js:2:80319) at Object.g [as onReady] (WAServiceMainContext.js:2:80569) at a (WAServiceMainContext.js:2:145625) at Function.<anonymous> (WAServiceMainContext.js:2:146998) at WAServiceMainContext.js:2:137477 at WAServiceMainContext.js:2:245633