Attachment: Download

Issue Description:

Given the following code which can be found in `main.swift` in the attached project

import Vapor

let app = try Application()
let router = try app.make(Router.self)

router.get("users") { req in
    let id = 1

    return "User #\(id)"
}

try app.run()
{\code}

The following error is thrown upon `swift run`

error: type 'PathComponentsRepresentable' does not conform to protocol 'ExpressibleByStringLiteral'
router.get("users") { req in
^
{\code}

While that error is technically correct, that's not the problem here. `router.get` is defined as

public func get<T>(_ path: PathComponentsRepresentable..., use closure: @escaping (Request) throws -> T) -> Route<Responder>
        where T: ResponseEncodable
{\code}

and `String` conforms to `PathComponentsRepresentable`. The above code runs fine if it's changed to

import Vapor

let app = try Application()
let router = try app.make(Router.self)

router.get("users") { req -> String in // CHANGE HERE: Explicit return type added
let id = 1

return "User #(id)"
}

try app.run()
{\code}