Fix error reporting for simple maps

src/Microsoft.OpenApi.Readers/ParseNodes/MapNode.cs

@@ -93,7 +93,7 @@ public override Dictionary<string, T> CreateMap<T>(Func<MapNode, T> map)
 
         public override Dictionary<string, T> CreateMapWithReference<T>(
             ReferenceType referenceType,
-            Func<MapNode, T> map)
+            Func<MapNode, T> map) 
         {
             var yamlMap = _node;
             if (yamlMap == null)
@@ -104,28 +104,37 @@ public override Dictionary<string, T> CreateMapWithReference<T>(
             var nodes = yamlMap.Select(
                 n =>
                 {
-                    var entry = new
-                    {
-                        key = n.Key.GetScalarValue(),
-                        value = map(new MapNode(Context, (YamlMappingNode)n.Value))
-                    };
-                    if (entry.value == null)
-                    {
-                        return null;  // Body Parameters shouldn't be converted to Parameters
-                    }
-                    // If the component isn't a reference to another component, then point it to itself.
-                    if (entry.value.Reference == null)
+                    var key = n.Key.GetScalarValue();
+                    (string key, T value) entry;
+                    try
                     {
-                        entry.value.Reference = new OpenApiReference()
+                        Context.StartObject(key);
+                        entry = (
+                            key: key,
+                            value: map(new MapNode(Context, (YamlMappingNode)n.Value))
+                        );
+                        if (entry.value == null)
+                        {
+                            return default;  // Body Parameters shouldn't be converted to Parameters
+                        }
+                        // If the component isn't a reference to another component, then point it to itself.
+                        if (entry.value.Reference == null)
                         {
-                            Type = referenceType,
-                            Id = entry.key
-                        };
+                            entry.value.Reference = new OpenApiReference()
+                            {
+                                Type = referenceType,
+                                Id = entry.key
+                            };
+                        }
+                     }
+                    finally
+                    {
+                        Context.EndObject();
                     }
                     return entry;
                 }
                 );
-            return nodes.Where(n => n != null).ToDictionary(k => k.key, v => v.value);
+            return nodes.Where(n => n != default).ToDictionary(k => k.key, v => v.value);
         }
 
         public override Dictionary<string, T> CreateSimpleMap<T>(Func<ValueNode, T> map)
@@ -137,10 +146,21 @@ public override Dictionary<string, T> CreateSimpleMap<T>(Func<ValueNode, T> map)
             }
 
             var nodes = yamlMap.Select(
-                n => new
+                n =>
                 {
-                    key = n.Key.GetScalarValue(),
-                    value = map(new ValueNode(Context, (YamlScalarNode)n.Value))
+                    var key = n.Key.GetScalarValue();
+                    try
+                    {
+                        Context.StartObject(key);
+                        YamlScalarNode scalarNode = n.Value as YamlScalarNode;
+                        if (scalarNode == null)
+                        {
+                            throw new OpenApiReaderException($"Expected scalar while parsing {typeof(T).Name}", Context);
+                        }
+                        return (key, value: map(new ValueNode(Context, (YamlScalarNode)n.Value)));
+                    } finally {
+                        Context.EndObject();
+                    }
                 });
             return nodes.ToDictionary(k => k.key, v => v.value);
         }

test/Microsoft.OpenApi.SmokeTests/ApiGurus.cs

@@ -70,8 +70,9 @@ JToken GetProp(JToken obj, string prop)
             }
         }
 
-        // Disable as some APIs are currently invalid [Theory(DisplayName = "APIs.guru")]
-        // [MemberData(nameof(GetSchemas))]
+        // Disable as some APIs are currently invalid
+        //[Theory(DisplayName = "APIs.guru")]
+        //[MemberData(nameof(GetSchemas))]
         public async Task EnsureThatICouldParse(string url)
         {
             var response = await _httpClient.GetAsync(url);