Fixes null extension bug

src/Microsoft.OpenApi.Readers/V2/OpenApiV2Deserializer.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft Corporation. All rights reserved.
+// Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license.
 
 using System.Collections.Generic;
@@ -113,11 +113,11 @@ public static IOpenApiAny LoadAny(ParseNode node)
 
         private static IOpenApiExtension LoadExtension(string name, ParseNode node)
         {
-            if (node.Context.ExtensionParsers.TryGetValue(name, out var parser))
+            if (node.Context.ExtensionParsers.TryGetValue(name, out var parser) && parser(
+                   OpenApiAnyConverter.GetSpecificOpenApiAny(node.CreateAny()),
+                   OpenApiSpecVersion.OpenApi2_0) is { } result)
             {
-                return parser(
-                    OpenApiAnyConverter.GetSpecificOpenApiAny(node.CreateAny()),
-                    OpenApiSpecVersion.OpenApi2_0);
+                return result;
             }
             else
             {

src/Microsoft.OpenApi.Readers/V3/OpenApiV3Deserializer.cs

@@ -171,11 +171,11 @@ public static IOpenApiAny LoadAny(ParseNode node)
 
         private static IOpenApiExtension LoadExtension(string name, ParseNode node)
         {
-            if (node.Context.ExtensionParsers.TryGetValue(name, out var parser))
+            if (node.Context.ExtensionParsers.TryGetValue(name, out var parser) && parser(
+                   OpenApiAnyConverter.GetSpecificOpenApiAny(node.CreateAny()),
+                   OpenApiSpecVersion.OpenApi3_0) is { } result)
             {
-                return parser(
-                    OpenApiAnyConverter.GetSpecificOpenApiAny(node.CreateAny()),
-                    OpenApiSpecVersion.OpenApi3_0);
+                return result;
             }
             else
             {

src/Microsoft.OpenApi/MicrosoftExtensions/OpenApiDeprecationExtension.cs

@@ -78,7 +78,7 @@ public void Write(IOpenApiWriter writer, OpenApiSpecVersion specVersion)
     /// <exception cref="ArgumentOutOfRangeException">When the source element is not an object</exception>
     public static OpenApiDeprecationExtension Parse(IOpenApiAny source)
     {
-        if (source is not OpenApiObject rawObject) throw new ArgumentOutOfRangeException(nameof(source));
+        if (source is not OpenApiObject rawObject) return null;
         var extension = new OpenApiDeprecationExtension();
         if (rawObject.TryGetValue(nameof(RemovalDate).ToFirstCharacterLowerCase(), out var removalDate) && removalDate is OpenApiDateTime removalDateValue)
             extension.RemovalDate = removalDateValue.Value;

src/Microsoft.OpenApi/MicrosoftExtensions/OpenApiEnumFlagsExtension.cs

@@ -45,7 +45,7 @@ public void Write(IOpenApiWriter writer, OpenApiSpecVersion specVersion)
     /// <exception cref="ArgumentOutOfRangeException">When the source element is not an object</exception>
     public static OpenApiEnumFlagsExtension Parse(IOpenApiAny source)
     {
-        if (source is not OpenApiObject rawObject) throw new ArgumentOutOfRangeException(nameof(source));
+        if (source is not OpenApiObject rawObject) return null;
         var extension = new OpenApiEnumFlagsExtension();
         if (rawObject.TryGetValue(nameof(IsFlags).ToFirstCharacterLowerCase(), out var flagsValue) && flagsValue is OpenApiBoolean isFlags)
         {

src/Microsoft.OpenApi/MicrosoftExtensions/OpenApiEnumValuesDescriptionExtension.cs

@@ -64,7 +64,7 @@ public void Write(IOpenApiWriter writer, OpenApiSpecVersion specVersion)
     /// <exception cref="ArgumentOutOfRangeException">When the source element is not an object</exception>
     public static OpenApiEnumValuesDescriptionExtension Parse(IOpenApiAny source)
     {
-        if (source is not OpenApiObject rawObject) throw new ArgumentOutOfRangeException(nameof(source));
+        if (source is not OpenApiObject rawObject) return null;
         var extension = new OpenApiEnumValuesDescriptionExtension();
         if (rawObject.TryGetValue("values", out var values) && values is OpenApiArray valuesArray)
         {

src/Microsoft.OpenApi/MicrosoftExtensions/OpenApiPagingExtension.cs

@@ -73,7 +73,7 @@ public void Write(IOpenApiWriter writer, OpenApiSpecVersion specVersion)
     /// <exception cref="ArgumentOutOfRangeException">When the source element is not an object</exception>
     public static OpenApiPagingExtension Parse(IOpenApiAny source)
     {
-        if (source is not OpenApiObject rawObject) throw new ArgumentOutOfRangeException(nameof(source));
+        if (source is not OpenApiObject rawObject) return null;
         var extension = new OpenApiPagingExtension();
         if (rawObject.TryGetValue(nameof(NextLinkName).ToFirstCharacterLowerCase(), out var nextLinkName) && nextLinkName is OpenApiString nextLinkNameStr)
         {

src/Microsoft.OpenApi/MicrosoftExtensions/OpenApiPrimaryErrorMessageExtension.cs

@@ -1,4 +1,4 @@
-// ------------------------------------------------------------
+// ------------------------------------------------------------
 //  Copyright (c) Microsoft Corporation.  All rights reserved.
 //  Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
 // ------------------------------------------------------------
@@ -39,7 +39,7 @@ public void Write(IOpenApiWriter writer, OpenApiSpecVersion specVersion)
     /// <returns>The <see cref="OpenApiPrimaryErrorMessageExtension"/>.</returns>
     public static OpenApiPrimaryErrorMessageExtension Parse(IOpenApiAny source)
     {
-        if (source is not OpenApiBoolean rawObject) throw new ArgumentOutOfRangeException(nameof(source));
+        if (source is not OpenApiBoolean rawObject) return null;
         return new()
         {
             IsPrimaryErrorMessage = rawObject.Value

src/Microsoft.OpenApi/MicrosoftExtensions/OpenApiReservedParameterExtension.cs

@@ -41,7 +41,7 @@ public bool? IsReserved
     /// <returns></returns>
     public static OpenApiReservedParameterExtension Parse(IOpenApiAny source)
     {
-        if (source is not OpenApiBoolean rawBoolean) throw new ArgumentOutOfRangeException(nameof(source));
+        if (source is not OpenApiBoolean rawBoolean) return null;
         return new()
         {
             IsReserved = rawBoolean.Value

test/Microsoft.OpenApi.Tests/MicrosoftExtensions/OpenApiReservedParameterExtensionTests.cs

@@ -17,6 +17,19 @@ public void Parses()
         Assert.NotNull(value);
         Assert.True(value.IsReserved);
     }
+
+    [Fact]
+    public void DoesNotThrowExceptionIfValueIsNull()
+    {
+        var oaiValue = new OpenApiObject
+        {
+            ["foo"] = new OpenApiString("foo")
+        };
+
+        var value = OpenApiReservedParameterExtension.Parse(oaiValue);
+        Assert.Null(value);
+    }
+
     [Fact]
     public void Serializes()
     {