ASP.NET Core 2 middleware error handling

[madskristensen]

When the HTML is malformed leading to an HTML parse error inside the WebMarkupMin middleware, there is no way to gracefully handle it.

Repro steps

1. Add the WebMarkupMin middleware and verify it minifies the response HTML
2. Add an unclosed <br tag anywhere on the page
3. Refresh the browser

Actual
The middleware throws an exception and the page is therefore not shown - but instead an error message is displayed if no custom error page is defined.

Expected
When an error occurs, simple just about the minification and serve the unminified. That way the page isn't broken and the user can see the content

[Taritsyn]

Hello, Mads!

This issue has been discussed many times (for example, “drop minification in case of errors”). Just nobody reads the documentation.

[madskristensen]

I did read it, but I don't know how to use the NullLogger. Any code samples?

[madskristensen]

The NullLogger fixes the issue with the original repro step. However, add the following to any HTML reponse and it breaks again:

<?xml:namespace prefix />

[madskristensen]

Also, another issue with the NullLogger is that it disables logging for everything in the application and not just WebMarkupMin. How about adding a Boolean property to the service options called something like options.ContinueOnError = true

[madskristensen]

Never mind. I got confused by the names ILogger and NullLogger which both exist in a MS nuget package

[Taritsyn]

Hello, Mads!

<?xml:namespace prefix />

This error is handled correctly.

I got confused by the names ILogger and NullLogger which both exist in a MS nuget package

Unfortunately, I began to use such type names still in 2013.

Expected
When an error occurs, simple just about the minification and serve the unminified. That way the page isn't broken and the user can see the content

In next release I will make NullLogger the logger by default.