Fixes up some errors

src/Umbraco.Core/IO/IOHelperExtensions.cs

@@ -5,6 +5,19 @@ namespace Umbraco.Core.IO
 {
     public static class IOHelperExtensions
     {
+        /// <summary>
+        /// Will resolve a virtual path URL to an absolute path, else if it is not a virtual path (i.e. starts with ~/) then
+        /// it will just return the path as-is (relative).
+        /// </summary>
+        /// <param name="ioHelper"></param>
+        /// <param name="path"></param>
+        /// <returns></returns>
+        public static string ResolveRelativeOrVirtualUrl(this IIOHelper ioHelper, string path)
+        {
+            if (string.IsNullOrWhiteSpace(path)) return path;
+            return path.StartsWith("~/") ? ioHelper.ResolveUrl(path) : path;
+        }
+
         /// <summary>
         /// Tries to create a directory.
         /// </summary>