ENH: Bring 404 page from lesson example

[jhlegarreta]

Bring 404 page from lesson example.

[netlify]

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Built with commit 255aba1

https://deploy-preview-112--carpentries-dmri.netlify.app

[kaitj]

Like the idea of the 404 page, but seems like it isn't loading the Carpentries template (at least in the netlify builds). I am guessing it is suppose to mirror parts of the theme, but with the 404 message.

[jhlegarreta]

Yes, looks like it's missing some parts of the theme. Will have a look as time permits.

[josephmje]

Suggested change

	layout: base
	layout: page

[josephmje]

Suggested change

	permalink: 404.html
	permalink: /404.html

[josephmje]

just left a few suggestions. not sure whether they will change the rendering or not.

[jhlegarreta]

Thanks for the review @josephmje .

I tried building the site locally and the 404 HTML takes the theme correctly, so maybe it's some netlify artifact.

[kaitj]

I am good with merging this in spite of Netlify not rendering. Did a cross-reference with the 404 page in the SDC-BIDS-IntroMRI repo and everything is the same.

I suggest taking a quick look following merge to make sure the published page renders correctly

[jhlegarreta]

We went ahead and merged this hypothesizing that it was maybe a netlify artifact what is shown in the picture here.

It turns out that netlify was correct, e.g.
https://carpentries-incubator.github.io/SDC-BIDS-dMRI/diffusion_tensor_imaging2/index.html

I've only been able to find a single relevant commit to the 404 page in the examples repository:
carpentries/lesson-example@d8f93f0

And we've realized that the example lesson does also suffer from the same issue:
https://carpentries.github.io/lesson-example/04-formatting2/index.html

Looks like we are missing something elsewhere. @tobyhodges @zkamvar do you happen to have an intuition of what could be missing?

We've realized that it's only happening on lesson pages; if you have enter an invalid URL on the main page, it seems to render correctly, e.g.
https://carpentries-incubator.github.io/SDC-BIDS-dMRI/test

Cross-referencing carpentries/lesson-example#335.

Thanks.

[jhlegarreta]

Cross-referencing #140.