thirdScriptError 运行错误

[jp1017]

14:46:27.786 项目 'gank-uni-app' 编译成功.
14:46:27.829 正在同步手机端程序文件...
14:46:28.496 同步手机端程序文件完成
14:46:28.516 正在重启...
14:46:30.994 App Show at App.vue:7
14:46:31.018 thirdScriptError
14:46:31.037 46:29.806 9548 9548 I console : Cannot read property '$root' of undefined;at pages/index/index page lifeCycleMethod onShow function
14:46:31.059 46:29.806 9548 9548 I console : TypeError: Cannot read property '$root' of undefined
14:46:31.081 46:29.806 9548 9548 I console : at getRootVueVm (D:/HBuilderX.1.5.4.20190127.full/HBuilderX/plugins/uniapp-cli/node_modules/@dcloudio/vue-cli-plugin-uni/packages/mpvue-page-factory/index.js:37:19)
14:46:31.103 46:29.806 9548 9548 I console : at e.onShow (D:/HBuilderX.1.5.4.20190127.full/HBuilderX/plugins/uniapp-cli/node_modules/@dcloudio/vue-cli-plugin-uni/packages/mpvue-page-factory/index.js:78:23)
14:46:35.334 thirdScriptError
14:46:35.355 46:34.156 9548 9548 I console : Cannot read property '$root' of undefined;at pages/index/index page onBackPress function
14:46:35.376 46:34.156 9548 9548 I console : TypeError: Cannot read property '$root' of undefined
14:46:35.397 46:34.156 9548 9548 I console : at getRootVueVm (D:/HBuilderX.1.5.4.20190127.full/HBuilderX/plugins/uniapp-cli/node_modules/@dcloudio/vue-cli-plugin-uni/packages/mpvue-page-factory/index.js:37:19)
14:46:35.419 46:34.156 9548 9548 I console : at e.onBackPress (D:/HBuilderX.1.5.4.20190127.full/HBuilderX/plugins/uniapp-cli/node_modules/@dcloudio/vue-cli-plugin-uni/packages/mpvue-page-factory/index.js:148:25)
14:46:35.925 thirdScriptError
14:46:35.946 46:34.743 9548 9548 I console : Cannot read property '$root' of undefined;at pages/index/index page onBackPress function
14:46:35.966 46:34.743 9548 9548 I console : TypeError: Cannot read property '$root' of undefined
14:46:35.986 46:34.743 9548 9548 I console : at getRootVueVm (D:/HBuilderX.1.5.4.20190127.full/HBuilderX/plugins/uniapp-cli/node_modules/@dcloudio/vue-cli-plugin-uni/packages/mpvue-page-factory/index.js:37:19)
14:46:36.006 46:34.743 9548 9548 I console : at e.onBackPress (D:/HBuilderX.1.5.4.20190127.full/HBuilderX/plugins/uniapp-cli/node_modules/@dcloudio/vue-cli-plugin-uni/packages/mpvue-page-factory/index.js:148:25)