Await before adding result to Items.["RequestModel"] fixes #70 (#74)

Author: NinoFloris

src/Saturn/Pipelines.fs

@@ -184,17 +184,18 @@ module PipelineHelpers =
   ///Tries to model from request and puts model into `Items.RequestModel`. If it won't be called content can be fetched using `Context.Controller` helpers.
   ///It won't crash the pipelines if fetching failed.
   ///It optionally takes custom culture name as arguments.
-  let fetchModel<'a> culture (nxt : HttpFunc) (ctx : HttpContext) : HttpFuncResult =
+  let fetchModel<'a> culture (nxt : HttpFunc) (ctx : HttpContext) : HttpFuncResult = task {
     let clt = culture |> Option.map System.Globalization.CultureInfo.CreateSpecificCulture
     try
-      let mdl =
+      let! mdl =
         match clt with
         | Some c -> ctx.BindModelAsync<'a>(c)
         | None -> ctx.BindModelAsync<'a>()
       ctx.Items.["RequestModel"] <- mdl
     with
     | _ -> ()
-    nxt ctx
+    return! nxt ctx
+  }
 
   let internal fetchUrl (nxt : HttpFunc) (ctx : HttpContext) : HttpFuncResult =
     if not (ctx.Items.ContainsKey "RequestUrl") then