Clean up GraphQL username retrieval

src/Tgstation.Server.Host/GraphQL/Types/UserName.cs

@@ -27,19 +27,14 @@ namespace Tgstation.Server.Host.GraphQL.Types
 		/// <param name="cancellationToken">The <see cref="CancellationToken"/> for the operation.</param>
 		/// <returns>A <see cref="ValueTask"/> resulting in the queried <see cref="UserName"/>, if present.</returns>
 		[TgsGraphQLAuthorize]
-		public static async ValueTask<UserName?> GetUserName(
+		public static ValueTask<UserName?> GetUserName(
 			long id,
 			[Service] IGraphQLAuthorityInvoker<IUserAuthority> userAuthority,
 			CancellationToken cancellationToken)
 		{
 			ArgumentNullException.ThrowIfNull(userAuthority);
-			var user = await userAuthority.InvokeTransformable<Models.User, User, UserGraphQLTransformer>(
+			return userAuthority.InvokeTransformableAllowMissing<Models.User, UserName, UserNameGraphQLTransformer>(
 				authority => authority.GetId(id, false, true, cancellationToken));
-
-			if (user == null)
-				return null;
-
-			return new UserName(user);
 		}
 
 		/// <summary>
@@ -51,5 +46,12 @@ namespace Tgstation.Server.Host.GraphQL.Types
 			: base(copy)
 		{
 		}
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="UserName"/> class.
+		/// </summary>
+		public UserName()
+		{
+		}
 	}
 }

src/Tgstation.Server.Host/Models/Transformers/UserNameGraphQLTransformer.cs

@@ -0,0 +1,20 @@
+namespace Tgstation.Server.Host.Models.Transformers
+{
+	/// <summary>
+	/// <see cref="ITransformer{TInput, TOutput}"/> for <see cref="GraphQL.Types.UserName"/>s.
+	/// </summary>
+	sealed class UserNameGraphQLTransformer : TransformerBase<User, GraphQL.Types.UserName>
+	{
+		/// <summary>
+		/// Initializes a new instance of the <see cref="UserNameGraphQLTransformer"/> class.
+		/// </summary>
+		public UserNameGraphQLTransformer()
+			: base(model => new GraphQL.Types.UserName
+			{
+				Id = model.Id!.Value,
+				Name = model.Name!,
+			})
+		{
+		}
+	}
+}

src/Tgstation.Server.Host/Models/User.cs

@@ -12,7 +12,8 @@ namespace Tgstation.Server.Host.Models
 	/// <inheritdoc cref="Api.Models.Internal.UserModelBase" />
 	public sealed class User : Api.Models.Internal.UserModelBase,
 		ILegacyApiTransformable<UserResponse>,
-		IApiTransformable<User, GraphQL.Types.User, UserGraphQLTransformer>
+		IApiTransformable<User, GraphQL.Types.User, UserGraphQLTransformer>,
+		IApiTransformable<User, GraphQL.Types.UserName, UserNameGraphQLTransformer>
 	{
 		/// <summary>
 		/// Username used when creating jobs automatically.