错误处理：提取错误上下文

I have a function which return error:

func foo(i int) error {
    err := errors.New("error here")

    if i == 1 {
        return errors.Wrap(err, "one")
    }

    if i == 2 {
        return errors.Wrap(err, "two")  
    }

    return nil
}

I want to handle an error in the calling function, but to do it, I need to know the context of error. Something like this:

err := foo(i) 

switch err.getContext() {
  case "foo":
  case "bar":
}

I have found causer interface, but I don't know how to use it here.

Or do I need to create the different types (struct) for each type of error here ?