The following legitimate comparison using switch statement

func SwitchOnUnixErrors() {
       err := unix.Rmdir("somepath")
       switch err {
       case unix.ENOENT:
               return
       case unix.EPERM:
               return
       }
       fmt.Println(err)
}

results in a warning:

switch on an error will fail on wrapped errors. Use errors.Is to check for specific errors

Apparently, whitelist of allowed direct comparisons, as implemented in allowed.go, is not used when analysing switch statements.