Simplifies authentication flow.

Refactors the authentication flow to streamline error handling.
Removes the `OneOf` return type and dedicated error records for wrong credentials and captcha requirements, returning null instead to indicate failure.
This change simplifies the calling code by allowing it to directly check for a null session, instead of having to handle different error types.

Author: Roxeez

src/GameforgeConnector/GameforgeClient.cs

@@ -7,10 +7,6 @@
 
 namespace GameforgeConnector;
 
-
-public record WrongCredentials;
-public record Captcha(string ChallengeId);
-
 public record GameforgeClientSettings(
     string InstallationId, 
     string ChromeVersion, 
@@ -26,7 +22,7 @@ public class GameforgeClient(GameforgeClientSettings settings)
         AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate | DecompressionMethods.Brotli,
     });
 
-    public async Task<OneOf<GameforgeClientSession, WrongCredentials, Captcha>> ConnectAsync(string email, string password)
+    public async Task<GameforgeClientSession?> ConnectAsync(string email, string password)
     {
         var fp = await settings.Fingerprint.CopyAndRefresh();
 
@@ -55,8 +51,6 @@ public async Task<OneOf<GameforgeClientSession, WrongCredentials, Captcha>> Conn
 
         return response.StatusCode switch
         {
-            HttpStatusCode.Conflict => new Captcha(ParseChallengeId(response)),
-            HttpStatusCode.Forbidden => new WrongCredentials(),
             HttpStatusCode.Created => new GameforgeClientSession(settings, ExtractToken(body)),
             _ => throw new InvalidOperationException($"Unexpected response {(int)response.StatusCode} {response.ReasonPhrase}: {body}")
         };

src/GameforgeConnector/GameforgeClientSession.cs

@@ -67,10 +67,10 @@ public async Task<List<GameAccount>> GetAccountsAsync()
         return accounts;
     }
 
-    public async Task<OneOf<GameTokenCreated, GameTokenCreationError>> GetGameTokenAsync(GameAccount account)
+    public async Task<string?> GetTokenAsync(GameAccount account)
     {
         if  (!await SendIovation(account.Id))
-            return new GameTokenCreationError("Failed to send iovation request");
+            return null;
 
         var id = Guid.NewGuid() + "-" + new Random().Next(1000, 9999);
 
@@ -108,12 +108,12 @@ public async Task<OneOf<GameTokenCreated, GameTokenCreationError>> GetGameTokenA
         var body = await response.Content.ReadAsStringAsync();
 
         if (response.StatusCode != HttpStatusCode.Created) 
-            return new GameTokenCreationError($"Failed to get game token: {(int)response.StatusCode} {response.ReasonPhrase}");
+            return null;
 
         var json = JObject.Parse(body);
         var code = json["code"]?.ToString();
 
-        return new GameTokenCreated(code!);
+        return code!;
     }
 
     private string GenerateThirdTypeUserAgent(string accountId)