被人吐槽最多的 if err != nil

参考阅读:

https://mp.weixin.qq.com/s/L_Sy4_6BURL4XWDK6bpEwg

https://mp.weixin.qq.com/s/XILveKzh07BOQnqxYDKQsA

https://mp.weixin.qq.com/s/nzoFI8ANBVDP9VPWfDgoHw