ModelStateDictionary.Simplify extension method

gistfile1.txt

/// <summary>
/// Simplifies the structure of a ModelStateDictionary instance to a "key => [ "error1", "error2", ... "errorN" ]" dictionary.
/// Also removes entries with no error messages.
/// </summary>
/// <param name="modelState"></param>
/// <returns></returns>
public static Dictionary<string, string[]> Simplify(this ModelStateDictionary modelState)
{
    return modelState.ToDictionary(
        entry => entry.Key, 
        entry => entry.Value.Errors
                            .Where(error => !string.IsNullOrEmpty(error.ErrorMessage) || error.Exception != null)
                            .Select(error => !string.IsNullOrEmpty(error.ErrorMessage) ? error.ErrorMessage : error.Exception.Message).ToArray())
                     .Where(entry => entry.Value.Any())
                     .ToDictionary(entry => entry.Key, entry => entry.Value);
}