Should Factory.CreateInstance ignore NLog.Web errors?

In my target I have a layout looking like this:

public Layout HostnameLayout { get; set; } = "${event-properties:hostname:whenEmpty=${aspnet-request-host:whenEmpty=${machinename}}}";

Basically, I want to try and render a hostname by looking at various properties. If the user specify a structured variable named hostname, I will use that. If not, I look for an aspnet-request-host. If not there I try to pull the machinename.

The main challenge here is that the CreateInstance method of the Factory class, throws an exception if someone adds my target to their code but not add the NLog.Web package. I want to allow people running without the NLog.Web package, but I don’t want the config causing an exception.

Is there some way to avoid this or should it maybe be allowed to reference layout renderers that may or may not be there?

[ThomasArdal]

Didn’t know about throwConfigExceptions=false. I had it in the sample code. Must have been a copy-paste from somewhere. It now makes total sense to me and I agree. If users set this to true, NLog should indeed complain.

[snakefoot]

If you want a soft dependency on NLog.Web and NLog.Web.AspNetCore. Then I guess you need to assign the layout on InitializeTarget instead of in constructor, and have some fallback mechanism if the wanted layoutrenderer is not yet available. See also my ramble here: #3557