message: code review - extract failure case to early bail
diff: @@ -50,11 +50,14 @@ impl Target {
  pub fn routes(&self) -> Result<Vec<Route>, failure::Error> {
  let mut routes = Vec::new();
  - if let Some(single_route) = &self.route {
  - if self.routes.is_some() {
  + // we should assert that only one of the two keys is specified in the user's toml.
  + if self.route.is_some() && self.routes.is_some() {
  failure::bail!("You can specify EITHER `route` or `routes` in your wrangler.toml");
  }
  + // everything outside of this module should consider `target.routes()` to be a Vec;
  + // the fact that you can specify singular or plural is a detail of the wrangler.toml contract.
  + if let Some(single_route) = &self.route {
  routes.push(Route {
  script: Some(self.name.to_owned()),
  pattern: single_route.to_string(),
  