Go wraps cannot throw errors

[krisbitney]

Describe the bug This is the generated interface for a module with a single method that returns a string:

type Module interface {
    Obscure(args *ArgsObscure) string
}

Since errors cannot be thrown in Go, we should handle them in the bindings as with do with Rust's Result type:

type Module interface {
    Obscure(args *ArgsObscure) (string, error)
}