@@ -51,7 +51,7 @@ private static async Task Start()
       var json = await File.ReadAllTextAsync(CredentialsPath);
       var token = JsonConvert.DeserializeObject<PKCETokenResponse>(json);
 
-      var authenticator = new PKCEAuthenticator(clientId!, token);
+      var authenticator = new PKCEAuthenticator(clientId!, token!);
       authenticator.TokenRefreshed += (sender, token) => File.WriteAllText(CredentialsPath, JsonConvert.SerializeObject(token));
 
       var config = SpotifyClientConfig.CreateDefault()
 
@@ -1,5 +1,7 @@
 using System;
 using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
 using Newtonsoft.Json;
 using NUnit.Framework;
 
@@ -18,5 +20,23 @@ public void PlayableItemConverter_CanSerialize()
         var serialized = JsonConvert.SerializeObject(context);
       });
     }
+
+    [Test]
+    public async Task PlayableItemConverter_Reserialize()
+    {
+      // This has lowercase field names since it's a spotify response
+      var fixture = await File.ReadAllTextAsync(
+        Path.Join(TestContext.CurrentContext.TestDirectory, "Fixtures/full_playlist_response.json")
+      );
+
+      var fullPlaylist = JsonConvert.DeserializeObject<FullPlaylist>(fixture);
+      // This whill have uppercase field names since we use default JsonConvert settings
+      var serialized = JsonConvert.SerializeObject(fullPlaylist);
+
+      Assert.DoesNotThrow(() =>
+      {
+        var deserialized = JsonConvert.DeserializeObject<FullPlaylist>(serialized);
+      });
+    }
   }
 }
@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>net5.0;netcoreapp3.1;netcoreapp2.2</TargetFrameworks>
+    <LangVersion>9.0</LangVersion>
     <IsPackable>false</IsPackable>
   </PropertyGroup>
 
@@ -18,4 +19,10 @@
     <ProjectReference Include="..\SpotifyAPI.Web.Auth\SpotifyAPI.Web.Auth.csproj" />
   </ItemGroup>
 
+   <ItemGroup>
+    <Content Include="Fixtures\*.*">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+  </ItemGroup>
+
 </Project>
@@ -46,9 +46,12 @@ protected APIException(SerializationInfo info, StreamingContext context) : base(
       {
         JObject bodyObject = JObject.Parse(body!);
 
-
         var error = bodyObject.Value<JToken>("error");
-        if (error.Type == JTokenType.String)
+        if (error == null)
+        {
+          return null;
+        }
+        else if (error.Type == JTokenType.String)
         {
           return error.ToString();
         }
 
@@ -15,24 +15,23 @@ public class PlayableItemConverter : JsonConverter
     {
       Ensure.ArgumentNotNull(serializer, nameof(serializer));
 
-      var token = JToken.ReadFrom(reader);
-      if (token.Type == JTokenType.Null)
+      if (JToken.ReadFrom(reader) is not JObject obj)
       {
         return null;
       }
 
-      var type = token["type"]?.Value<string>();
-      if (type == "track")
+      var type = obj.GetValue("type", StringComparison.OrdinalIgnoreCase)?.Value<string>();
+      if (string.Equals(type, "track", StringComparison.OrdinalIgnoreCase))
       {
-        var obj = new FullTrack();
-        serializer.Populate(token.CreateReader(), obj);
-        return obj;
+        var track = new FullTrack();
+        serializer.Populate(obj.CreateReader(), track);
+        return track;
       }
-      else if (type == "episode")
+      else if (string.Equals(type, "episode", StringComparison.OrdinalIgnoreCase))
       {
-        var obj = new FullEpisode();
-        serializer.Populate(token.CreateReader(), obj);
-        return obj;
+        var episode = new FullEpisode();
+        serializer.Populate(obj.CreateReader(), episode);
+        return episode;
       }
       else
       {
Original file line number	Diff line number	Diff line change
`@@ -46,9 +46,12 @@ protected APIException(SerializationInfo info, StreamingContext context) : base(`
`46`	`46`	`{`
`47`	`47`	`JObject bodyObject = JObject.Parse(body!);`
`48`	`48`
`49`		`-`
`50`	`49`	`var error = bodyObject.Value<JToken>("error");`
`51`		`- if (error.Type == JTokenType.String)`
	`50`	`+ if (error == null)`
	`51`	`+ {`
	`52`	`+ return null;`
	`53`	`+ }`
	`54`	`+ else if (error.Type == JTokenType.String)`
`52`	`55`	`{`
`53`	`56`	`return error.ToString();`
`54`	`57`	`}`
Original file line number	Diff line number	Diff line change
`@@ -15,24 +15,23 @@ public class PlayableItemConverter : JsonConverter`
`15`	`15`	`{`
`16`	`16`	`Ensure.ArgumentNotNull(serializer, nameof(serializer));`
`17`	`17`
`18`		`- var token = JToken.ReadFrom(reader);`
`19`		`- if (token.Type == JTokenType.Null)`
	`18`	`+ if (JToken.ReadFrom(reader) is not JObject obj)`
`20`	`19`	`{`
`21`	`20`	`return null;`
`22`	`21`	`}`
`23`	`22`
`24`		`- var type = token["type"]?.Value<string>();`
`25`		`- if (type == "track")`
	`23`	`+ var type = obj.GetValue("type", StringComparison.OrdinalIgnoreCase)?.Value<string>();`
	`24`	`+ if (string.Equals(type, "track", StringComparison.OrdinalIgnoreCase))`
`26`	`25`	`{`
`27`		`- var obj = new FullTrack();`
`28`		`- serializer.Populate(token.CreateReader(), obj);`
`29`		`- return obj;`
	`26`	`+ var track = new FullTrack();`
	`27`	`+ serializer.Populate(obj.CreateReader(), track);`
	`28`	`+ return track;`
`30`	`29`	`}`
`31`		`- else if (type == "episode")`
	`30`	`+ else if (string.Equals(type, "episode", StringComparison.OrdinalIgnoreCase))`
`32`	`31`	`{`
`33`		`- var obj = new FullEpisode();`
`34`		`- serializer.Populate(token.CreateReader(), obj);`
`35`		`- return obj;`
	`32`	`+ var episode = new FullEpisode();`
	`33`	`+ serializer.Populate(obj.CreateReader(), episode);`
	`34`	`+ return episode;`
`36`	`35`	`}`
`37`	`36`	`else`
`38`	`37`	`{`