Warning that does not stop build?

I use errorf for errors that break my content, such as missing target for my include shortcode or wrong values for our company-specific metadata. It stops the build and I want it to stop the build.

However, I’d like to have an option to display a WARNING that does not stop the build. I know Hugo can do this, for example when I have no _default layouts defined. Is there a function I can use? I can’t find it anywhere.


As you know, Hugo prints the WARN messages to prompt the transition from the old function to the new function. Those messages will be printed from Go code. I do not know the function to display WARN from a Hugo theme and I think that the function does not exist.