server: enable nullable annotations in legacy files

src/Yavsc.Server/Helpers/BillingHelpers.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 using System.Globalization;
 using Yavsc.Billing;
 using Yavsc.Models.Billing;

src/Yavsc.Server/Helpers/EstimateSignatureFileHelper.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 using System.Security.Claims;
 using System.Text;
 using System.Text.Json;

src/Yavsc.Server/Helpers/FileSystemHelpers.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 
 
 using System.Security.Claims;

src/Yavsc.Server/Helpers/HtmlHelpers.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 using Microsoft.AspNetCore.Html;
 using Microsoft.AspNetCore.Http;
 using Yavsc.Models.Drawing;

src/Yavsc.Server/Helpers/PayPalHelpers.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 using Microsoft.Extensions.Logging;
 using Yavsc.Models.Billing;
 using Microsoft.AspNetCore.Http;

src/Yavsc.Server/Helpers/RequestHelper.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 using System.Net;
 using System.Net.Http.Headers;
 using Yavsc.Server.Model;

src/Yavsc.Server/Helpers/ServiceExtensions.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 using Microsoft.AspNetCore.Authentication;
 using Microsoft.AspNetCore.Authentication.JwtBearer;
 using Microsoft.Extensions.Configuration;

src/Yavsc.Server/Helpers/UserHelpers.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 using Microsoft.EntityFrameworkCore;
 using System.Security.Claims;
 using Yavsc.Models;