${aspnet-request-form} raises exception in ASP.NET Core

[mcliment]

Type (choose one):

• Bug

NLog version: 4.5.10

NLog.Web/NLog.Web.AspNetCore version: 4.7.0

NLog.Extensions.Logging version:

Platform: .NET Core 2

Current NLog config (xml or C#, if relevant)

Not relevant, just add ${aspnet-request-form} to any target in the ASP.NET Core demo.

In case of a BUG:

• What is the current result?

Raises an Invalid Operation Exception with message Incorrect Content-Type: .

• What is the expected result?

To ignore requests that don't have posted form data.

• Did you checked the Internal log?

Yes.

• Please post full exception details (message, stacktrace, inner exceptions)

I provide a PR.

• Are there any workarounds? yes/no

No that I know.

• Is there a version in which it did work?

4.7.0 is the first to have this renderer.

• Can you help us by writing an unit test?

Included in the following PR.