After the code has been added to make add to head assignable also to the footer, there are constant render warnings User error: "1" is an invalid render array key in Drupal\Core\Render\Element::children() that come from the bad render array added to the footer.
Add some markup to the footer with add_to_head.
Remove the line 'add-to-head--' . $profile['name'], from add_to_head_page_bottom() - it copies the approach from the add_to_head_page_attachments_alter() but this approach does not work in the footer context.
Provide a patch. This is an easy fix but I can provide a patch if needed.
Needs review
1.0
Code
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It's likely this issue predates Contrib.social: some issue and comment data are missing.
Incase anyone has a similar issue, this was causing a WSOD when the devel module was enabled.
Disabling devel allowed me to see the error and find this issue.
If you have multiple scripts it will not work due to a cache issue.
Here is a patch that fixes the issue.