NetJSON: Serializing anonymous objects throws an exception

Given the following models:

public struct LogEvent
{
    public DateTime Timestamp { get; set; }
    public Level Level { get; set; }
    public string Entry { get; set; }
}

public enum Level
{
    Debug,
    Trace
}

When trying to serialize the following:

var logEvents = Enumerable.Range(1, 100)
        .Select(n => new LogEvent 
        {
            Timestamp = DateTime.UtcNow,
            Level = n % 2 == 0 ? Level.Debug : Level.Trace,
            Entry = n.ToString()
        });

var anonymousObjects = logEvents
    .Select(x => 
        new {
            TimestampEpoch = x.Timestamp,
            x.Level,
            Message = x.Entry
        }
    );

var defaultSettings = new NetJSONSettings { CamelCase = true, SkipDefaultValue = false };
var json = NetJSON.NetJSON.Serialize(anonymousObjects, defaultSettings);

Throws: TypeInitializationException: The type initializer for ‘NetJSONCachedSerializer`1’ threw an exception.

Removing the defaultSettings also results in the same error.

Note that serializing logEvents does not result in any exceptions and the problem is when the result is projected to anonymous objects.