quick Umbraco V7 question. I'm trying to programmatically remove a load of Vorto properties from a V7 site prior to upgrading, however I keep hitting 'Collection was modified; enumeration operation may not execute.' error when running the following code:
var contentTypes = _contentTypeService.GetAllContentTypes();
        foreach (var cts in contentTypes.Where(x => x.Id != 10546))
        {
            var vortoPropsToDelete = cts.PropertyTypes.Where(x => x.PropertyEditorAlias == "Our.Umbraco.Vorto");
            foreach (var vortoProp in vortoPropsToDelete)
            {
                cts.RemovePropertyType(vortoProp.Alias);
            }
            _contentTypeService.Save(cts);
        }
I can't work out were I'm going wrong...
 
    