Merge branch 'main' into 2521-bug-changset-mapping-from-tfvc-repo-to-git-repo-fails-during-work-item-migration

Author: MrHinsh

src/MigrationTools.Clients.TfsObjectModel/Processors/TfsWorkItemMigrationProcessor.cs

@@ -229,7 +229,7 @@ private void ValidateAllUsersExistOrAreMapped(List<WorkItemData> sourceWorkItems
         {
             contextLog.Information("Validating::Check that all users in the source exist in the target or are mapped!");
             IdentityMapResult usersToMap = CommonTools.UserMapping.GetUsersInSourceMappedToTargetForWorkItems(this, sourceWorkItems);
-            if (usersToMap.IdentityMap != null && usersToMap.IdentityMap.Count > 0)
+            if (usersToMap != null && usersToMap.IdentityMap != null && usersToMap.IdentityMap.Count > 0)
             {
                 Log.LogWarning("Validating Failed! There are {usersToMap} users that exist in the source that do not exist "
                     + "in the target. This will not cause any errors, but may result in disconnected users that could have "