增加应用初始化前调用 getWindowOffset，getCurrentPages 的兼容性处理

src/core/service/plugins/app/create-app.js

@@ -9,6 +9,10 @@ export function getApp () {
 export function getCurrentPages (isAll = false) {
   const pages = []
   const app = getApp()
+  if (!app) {
+    console.error('app is not ready')
+    return []
+  }
   const childrenVm = app.$children[0]
   if (childrenVm && childrenVm.$children.length) {
     const tabBarVm = childrenVm.$children.find(vm => vm.$options.name === 'TabBar')
@@ -47,7 +51,7 @@ export function getCurrentPages (isAll = false) {
     if (currentPage.$page.path !== app.$route.path) { // 删除已经准备销毁的上个页面
       pages.splice(length - 1, 1)
     }
-  }
+  }
 
   return pages
 }

src/platforms/h5/helpers/get-window-offset.js

@@ -7,19 +7,24 @@ export default function getWindowOffset () {
   if (uni.canIUse('css.var')) {
     const style = document.documentElement.style
     return {
-      top: parseInt(style.getPropertyValue('--window-top')),
-      bottom: parseInt(style.getPropertyValue('--window-bottom'))
+      top: parseInt(style.getPropertyValue('--window-top')) || 0,
+      bottom: parseInt(style.getPropertyValue('--window-bottom')) || 0
     }
   }
 
   let top = 0
+  let bottom = 0
   const pages = getCurrentPages()
   if (pages.length) {
     const pageVm = pages[pages.length - 1].$parent.$parent
     top = pageVm.showNavigationBar && pageVm.navigationBar.type !== 'transparent' ? NAVBAR_HEIGHT : 0
   }
+  const app = getApp()
+  if (app) {
+    bottom = app.$children[0].showTabBar ? TABBAR_HEIGHT : 0
+  }
   return {
     top,
-    bottom: getApp().$children[0].showTabBar ? TABBAR_HEIGHT : 0
+    bottom
   }
 }