check navigator before use it in switch (#1338)
check navigator before use it in switch (#1338)


bccsafe/ant-design-mobile,ant-design/ant-design-mobile,ant-design/ant-design-mobile,bccsafe/ant-design-mobile,bccsafe/ant-design-mobile,bccsafe/ant-design-mobile,ant-design/ant-design-mobile,bccsafe/ant-design-mobile,ant-design/ant-design-mobile