In my markdown file:

When I am trying to run Hugo, the following error comes out:
execute of template failed: template: _default/_markup/render-image.html:172:12: executing “_default/_markup/render-image.html” at <$r.Height>: can’t evaluate field Height in type string
I checked the render-image.html. Looks like it cannot deal with gif file correctly.
How can I exclude gif files from being handled by the image filter?