Add error handling example to pokedex.

examples/pokedex/app/ErrorPage.elm

@@ -102,7 +102,7 @@ view error model =
             , title = "Invalid pokedex number"
             }
 
-        _ ->
+        NotFound ->
             { body =
                 [ Html.div []
                     [ Html.p [] [ Html.text "Page not found. Maybe try another URL?" ]
@@ -121,6 +121,16 @@ view error model =
             , title = "This is a NotFound Error"
             }
 
+        InternalError errorMessage ->
+            { body =
+                [ Html.div []
+                    [ Html.h2 [] [ Html.text "Something's Not Right Here" ]
+                    , Html.p [] [ Html.text errorMessage ]
+                    ]
+                ]
+            , title = "Internal Server Error"
+            }
+
 
 statusCode : ErrorPage -> number
 statusCode error =

examples/pokedex/app/Route/ErrorHandling.elm

@@ -0,0 +1,77 @@
+module Route.ErrorHandling exposing (ActionData, Data, Model, Msg, route)
+
+import BackendTask exposing (BackendTask)
+import ErrorPage exposing (ErrorPage)
+import FatalError exposing (FatalError)
+import Head
+import Html exposing (text)
+import PagesMsg exposing (PagesMsg)
+import RouteBuilder exposing (App, StatefulRoute, StatelessRoute)
+import Server.Request as Request exposing (Parser)
+import Server.Response as Response exposing (Response)
+import Shared
+import View exposing (View)
+
+
+type alias Model =
+    {}
+
+
+type alias Msg =
+    ()
+
+
+type alias RouteParams =
+    {}
+
+
+type alias ActionData =
+    {}
+
+
+route : StatelessRoute RouteParams Data ActionData
+route =
+    RouteBuilder.serverRender
+        { head = head
+        , data = data
+        , action = \_ -> Request.skip "No action."
+        }
+        |> RouteBuilder.buildNoState { view = view }
+
+
+type alias Data =
+    { darkMode : Maybe String }
+
+
+data : RouteParams -> Parser (BackendTask FatalError (Response Data ErrorPage))
+data routeParams =
+    Request.succeed
+        (BackendTask.fail
+            (FatalError.fromString "This error should be displayed by the error handling!")
+        )
+
+
+head :
+    App Data ActionData RouteParams
+    -> List Head.Tag
+head static =
+    []
+
+
+view :
+    App Data ActionData RouteParams
+    -> Shared.Model
+    -> View (PagesMsg Msg)
+view static sharedModel =
+    { title = "Cookie test"
+    , body =
+        [ case static.data.darkMode of
+            Just darkMode ->
+                text <|
+                    "Dark mode: "
+                        ++ darkMode
+
+            Nothing ->
+                text "No dark mode preference set"
+        ]
+    }