NLog 3.1.0 event context does not work - nlog

Question

This is not so much as a question as it is a warning, and a bit of a rant.
I have the following NLog configuration file:
<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
throwExceptions="true">
<!--
See https://github.com/nlog/nlog/wiki/Configuration-file
for information on customizing logging rules and outputs.
-->
<targets>
<target xsi:type="File" name="f" fileName="${basedir}/logs/NLog_${shortdate}.log"
layout="${date} ${uppercase:${level}} ${message}" />
<target xsi:type="File" name="eventFile" fileName="${basedir}/logs/EventFile_${shortdate}.log"
layout="${date} ${uppercase:${level}} The answer is ${event-context:item=Universe}" />
</targets>
<rules>
<logger name="MyLogger" minlevel="Trace" writeTo="f" />
<logger name="EventLogger" minlevel="Debug" writeTo="eventFile" />
</rules>
</nlog>
I am using the following code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using NLog;
using NLog.Config;
using NLog.Targets;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
try
{
Logger eventLogger = LogManager.GetLogger("EventLogger");
LogEventInfo eventInfo = new LogEventInfo(LogLevel.Debug, "EventLogger", "message");
eventInfo.Properties["Universe"] = 42;
eventLogger.Debug(eventInfo);
}
catch (Exception ex)
{
int a = 1;
}
int b = 1;
}
}
}
I used NuGet to download NLog for this application. It gave me NLog version 3.1.0.0. When I run this application, the exception handler is invoked, and the inner exception complains that a dictionary has been modified and therefore can no longer be enumerated.
Earlier, I had downloaded NLog 3.0.0.0 from another source. I replaced the 3.1.0.0 reference in my application with a reference to the 3.0.0.0 version, and the exception did not occur.
I am a brand new user of NLog, and this is the second serious bug I have found. The first one was that if a log is created with a log level of "Off", which is perfectly legal, an index out of range exception is thrown. This is because the integer value of an enumeration of log levels for "Off" is 6, and that number is used as an index into an array that only has six elements (thus, its highest index is 5).
I realize that NLog is an open-source project and thus does not have guarantees, but given its popularity, I would have expected that there would be much better test procedures in place than there seem to be.
RobR