> My point is that translating an error from one call to the previous is neither generic nor pointless.

The first pattern does not do that. The second one is still mostly pointless generic boilerplate:

    blah, err := 
    if err != nil {
        return nil, errors.New()
    }

is all boilerplate, only two parts are not: the call itself and the error message.

> An exception and line-number (and a call-stack dump) is great for a developer, but a good textual error message is needed for a real user.

1. having exceptions doesn't preclude handling them and writing user-readable error messages

2. exceptions are not the only alternative to C-style error handling