Recent post title not being listed correctly

[darsnack]

Describe the issue
The recent posts under https://fluxml.ai/blog/ are generated by an hfun in Franklin.jl. The title is set to a page environment variable unless it is unspecified, in which case it gets a generic name like "Post 10". Currently, all blog posts have titles, but not all of them are generated correctly by the hfun.

To Reproduce
Steps to reproduce the behavior (include links to pages or assets):

1. "Post 10" https://fluxml.ai/blog/ on corresponds to https://fluxml.ai/blogposts/2021-12-1-flux-numfocus/
2. In the source for the post, the title environment variable is set
3. The hfun will read the environment variable and give a default if it is nothing:

   fluxml.github.io/utils.jl

   Line 15 in 660e649

   titles[i] = something(pagevar(url, :title), "Post $i")

   (currently that is what it is doing)
4. If you remove the something logic from the code, then you get an error about assigning Nothing to a Vector{String}, confirming that pagevar(url, :title) is returning nothing when it should return the title set in Step 2.

Step 4 makes me think this is Franklin issue @tlienart.

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