fix error reporting

Signed-off-by: Avinal Kumar <avinal.xlvii@gmail.com>

public/index.html

@@ -21,7 +21,7 @@
     <script src="https://cdn.jsdelivr.net/npm/prismjs@1.29.0/plugins/autoloader/prism-autoloader.min.js"></script>
     <script>
         var app = Elm.Main.init({ node: document.getElementById("app") });
-
+        var renderSuccess = false;
         app.ports.sendString.subscribe(function (markdowndata) {
 
             var numberOfHeadings = 0;
@@ -68,11 +68,17 @@
                     return Prism.highlight(code, grammar, lang);
                 }
             })
-            document.getElementById("insert-here").innerHTML = marked.parse(markdowndata, function () {
-                app.ports.isRenderComplete.send(true);
+            document.getElementById("insert-here").innerHTML = marked.parse(markdowndata, function (err, parsed) {
+                if (err) {
+                    console.log(err);
+                } else {
+                    renderSuccess = true;
+                }
             });
             // document.getElementById("toc-entries").innerHTML = toc;
         });
+
+        app.ports.isRenderComplete.send(renderSuccess);
     </script>
 </body>
 

src/Blog.elm

@@ -19,6 +19,7 @@ type alias Model =
     , markdownUrl : String
     , success : Bool
     , fragment : String
+    , error : Maybe String
     }
 
 
@@ -38,6 +39,7 @@ initialModel =
     , markdownUrl = ""
     , success = False
     , fragment = ""
+    , error = Nothing
     }
 
 
@@ -215,11 +217,11 @@ update msg model =
                 Ok blog ->
                     ( { model | blog = Just blog, success = True }, sendString blog.content )
 
-                Err _ ->
-                    ( { model | success = False }, Cmd.none )
+                Err err ->
+                    ( { model | success = False, error = Just err }, Cmd.none )
 
-        DataReceived (Err _) ->
-            ( { model | success = False }, Cmd.none )
+        DataReceived (Err err) ->
+            ( { model | success = False, error = Just (errorToString err) }, Cmd.none )
 
         ScrollToFragment _ _ ->
             ( model, scrollOnFragment model.fragment )
@@ -324,8 +326,8 @@ splitMetaContent data =
         Ok meta ->
             Ok { meta = meta, content = content }
 
-        Err _ ->
-            Err "YAML front matter parsing failed"
+        Err err ->
+            Err ("YAML front matter parsing failed: " ++ Yaml.errorToString err)
 
 
 metaDecoder : Decoder YamlMeta