Backports fixes to SQL parameterization and PetaPoco mem updates

src/Umbraco.Core/Services/MediaService.cs

@@ -402,6 +402,10 @@ namespace Umbraco.Core.Services
         public IEnumerable<IMedia> GetDescendants(int id)
         {
             var media = GetById(id);
+            if (media == null)
+            {
+                return Enumerable.Empty<IMedia>();
+            }
             return GetDescendants(media);
         }
 
@@ -1198,4 +1202,4 @@ namespace Umbraco.Core.Services
         public static event TypedEventHandler<IMediaService, RecycleBinEventArgs> EmptiedRecycleBin;
         #endregion
     }
-}
+}