Something funny happened, an issue solved now but still puzzling as I can still reproduce the behavior. Maybe that feedback could be of interest to developers. I am not sure if you guys would consider this a bug or just a counter-intuitive behavior 
I had a shortcode with this:
<figure class=“aside”>
{{ .Inner | markdownify }}
</figure>
and it used to work. then I needed a render-image.html specific to the homepage so I added “type: home” added to its frontmatter and made it, fine, but too fine: it created that error on a template not used at all on the homepage but in other pages:
kiddygirland.md:162:1": failed to render shortcode “ff”: failed to process shortcode: “ff.html:2:12”: execute of template failed at : error calling markdownify: “/home/drm/WEBSITE/content/_index.md:1:1”: “/home/drm/WEBSITE/themes/hugo-book/layouts/home/_markup/render-image.html:17:13”: execute of template failed at <$img.Width>: error calling Width: this method is only available for image resources
/home/drm/WEBSITE/content/docs/Love/Anime_analysis/kiddygirland.md:162:1:
I substitute the .Page.RenderString method to the obsolete markdownify and now it’s fine. I’m probably missing key differences between those functions/methods, but I wonder, why did it complain now and mentioned the homepage which doesn’t use this shortcode ?!
It mentioned:
/home/drm/WEBSITE/content/_index.md:1:1:
---
title: Purpose of this website
and:
/home/drm/WEBSITE/themes/hugo-book/layouts/home/_markup/render-image.html:16:13:
{{ if gt $img.Width 1540 }}
Versions:
Linux drm-4236wv5 6.2.9-arch1-1 #1 SMP PREEMPT_DYNAMIC Thu, 30 Mar 2023 14:51:14 +0000 x86_64 GNU/Linux
hugo v0.111.3-5d4eb5154e1fed125ca8e9b5a0315c4180dab192+extended linux/amd64 BuildDate=2023-03-12T11:40:50Z VendorInfo=gohugoio