Fixed possible null reference exceptions

src/Umbraco.Web.BackOffice/Trees/ContentTreeController.cs

@@ -1,29 +1,26 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Net;
+using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
 using Umbraco.Core;
+using Umbraco.Core.Configuration.Models;
 using Umbraco.Core.Models;
 using Umbraco.Core.Models.Entities;
-using Umbraco.Core.Services;
-using Umbraco.Web.Actions;
-using Umbraco.Web.Models.Trees;
-using Umbraco.Web.Models.ContentEditing;
-using Umbraco.Web.Search;
 using Umbraco.Core.Security;
-using Constants = Umbraco.Core.Constants;
-using Umbraco.Web.Common.Attributes;
-using Umbraco.Web.Common.Exceptions;
-using Umbraco.Web.WebApi;
-using Umbraco.Core.Configuration.Models;
-using Microsoft.Extensions.Options;
-using Umbraco.Web.Trees;
-using Microsoft.AspNetCore.Authorization;
-using Microsoft.AspNetCore.Mvc;
-using Umbraco.Web.Common.Authorization;
+using Umbraco.Core.Services;
 using Umbraco.Core.Trees;
+using Umbraco.Web.Actions;
+using Umbraco.Web.Common.Attributes;
+using Umbraco.Web.Common.Authorization;
+using Umbraco.Web.Models.ContentEditing;
+using Umbraco.Web.Models.Trees;
+using Umbraco.Web.Search;
+using Umbraco.Web.Trees;
+using Umbraco.Web.WebApi;
 
 namespace Umbraco.Web.BackOffice.Trees
 {
@@ -240,6 +237,12 @@ namespace Umbraco.Web.BackOffice.Trees
         protected override ActionResult<IEnumerable<IEntitySlim>> GetChildEntities(string id, FormCollection queryStrings)
         {
             var result = base.GetChildEntities(id, queryStrings);
+
+            if (!(result.Result is null))
+            {
+                return result.Result;
+            }
+
             var culture = queryStrings["culture"].TryConvertTo<string>();
 
             //if this is null we'll set it to the default.