Using hugo extended

Regarding this comment and this comment. I think a lot may have changed since then because hugo serve throws this error with the basic version

Error building site: execute of template failed: template: _default/_markup/render-image.html:5:23: executing "_default/_markup/render-image.html" at <$image.Resize>: error calling Resize: image: this feature is not available in your current Hugo version, see https://goo.gl/YMrWcn for more information

What does hugo version return?

Latest.

WEBP support exists only in Hugo Extended.

Other than the addition of the above new feature nothing has changed.

Alright.