private static Exception ReportBuildProblem(IEnumerable <KeyValuePair <Type, Type> > views, ArgumentException exception) { var overSizedCounts = views.GroupBy(x => x.Key) .Select(x => new { x.Key.Name, Count = x.Count() }) .Where(x => x.Count > 1) .ToList(); if (overSizedCounts.Count == 0) { // no idea what the error is - so throw the original return(exception.MvxWrap("Unknown problem in ViewModelViewLookup construction")); } else { var overSizedText = string.Join(",", overSizedCounts); return(exception.MvxWrap( "Problem seen creating View-ViewModel lookup table - you have more than one View registered for the ViewModels: {0}", overSizedText)); } }