when use polar coordinate with 'reflect('y')', the rendering is blank/当使用极坐标系时，设置y轴镜像，渲染空白，设置x轴镜像，渲染正常，但是设置y轴镜像的同时，设置innerRadius为大于0,渲染又正常

[muxinlove]

- [ ] I have searched the issues of this repository and believe that this is not a duplicate.

Reproduction link

https://antv-g2.gitee.io/zh/examples/radar/radar#basic

Steps to reproduce

set reflect is 'y'

chart.coordinate('polar', {
  radius: 0.8,
}).reflect('y')

Environment	Info
g2	4.0.15
System	mac
Browser	chrome

[hustcc]

你为啥要设置 .reflect('y')，你期望的效果是什么？