TD-4790 Write unit tests for tags added on optional competencies in the supervisor view

Author: sherif-olaboye

DigitalLearningSolutions.Data/Helpers/NewlineSeparatedStringListHelper.cs

@@ -17,7 +17,10 @@ public static string RemoveStringFromNewlineSeparatedList(string list, int index
         public static string AddStringToNewlineSeparatedList(string? list, string newItem)
         {
             var options = list != null ? SplitNewlineSeparatedList(list) : new List<string>();
-            options.Add(newItem?.Trim());
+            if (!string.IsNullOrWhiteSpace(newItem))
+            {
+                options.Add(newItem.Trim());
+            }
             return JoinNewlineSeparatedList(options);
         }