Liquid Exception comparison of Array with Array failed

[patrik-u]

I have a github pages site which suddenly started generating generic errors whenever I committed changes (been a while since i committed, last was in may):

The page build failed for the `master` branch with the following error:

Page build failed. For more information, see https://docs.github.com/en/github/working-with-github-pages/troubleshooting-jekyll-build-errors-for-github-pages-sites#troubleshooting-build-errors.

Wasn't very helpful, so contacted github support and they saw the following error in their logs:

Liquid Exception: Liquid error (/tmp/jekyll-remote-theme-20200807-6-1r5fb81/_includes/nav.html line 9): comparison of Array with Array failed included in /_layouts/default.html

Not very helpful so I after some trial and error getting the site to compile locally I managed to replicate the error. After more trial and error I found that if files under _post/ starts with numbers it caused the error to happen. Removing them and the error goes away. Heureka! So I did the changes committed it to my github pages and...

Page build failed.

So I can no longer reproduce the error locally, and build fails on github pages. I've contacted the support and maybe there is a different error this time.

[pdmosses]

@patrik-u if you'd like us to look at this, could you create a small test repository that exhibits the issue, and post a link to it?

BTW, you refer to _post/, but the directory Jekyll uses for posts is named _posts/, and Jekyll seems to expect the file names to start with the year.

[patrik-u]

That was a typo, the folder is indeed _posts/

[patrik-u]

Added a repository here:

https://github.com/patrik-u/just-the-docs-issue

It doesn't render exactly as the github pages site (not sure why). You can see the error when running and it goes away if you rename the files in _posts/ or remove the folder.

[pdmosses]

Thanks, that helped. I don't understand why the sorting fails, but as a workaround, try
adding the attached version of nav.html to _includes, and adding nav_exclude: true to all files in _posts.

nav.html.zip

[patrik-u]

Thanks that solved it for me.

[pdmosses]

I'll submit a PR with that update to nav.html.

The Jekyll failure was due to nav.html including pages with nav_exclude: true when sorting unordered pages on their titles. Your 404.md has the following in its front matter:

title: 404
permalink: /404.html
nav_exclude: true

Jekyll treats 404 as a number, and sorting fails when comparing numbers with strings...

The simplest way to make your repository work (without the fix to nav.html) is simply to change title: 404 in 404.md to title: "404". It isn't necessary to add nav_exclude: true to the files in _posts.

[patrik-u]

Thanks, that worked.

[pdmosses]

The reported Liquid exception is due to sorting an array that contains mixed types of values. In this case, the title of one file was parsed as a number; but it can also happen when nav_order fields are both numbers and strings.

Jekyll/Liquid error reports can be confusing, and the theme code should try to ensure that they never arise.