fix: tag.innerHTML.replace is not a function when no module config is provided

[cernymatej]

🐛 The bug

When the fontMetrics configuration is omitted in nuxt.config.ts, pages fail to render with the following error:
[500] tag.innerHTML.replace is not a function.

🛠️ To reproduce

https://stackblitz.com/edit/github-rbztbr?file=nuxt.config.ts

🌈 Expected behaviour

No error should be thrown in the absence of fontMetrics in nuxt.config.ts

ℹ️ Additional context

No response

[danielroe]

This is likely this upstream bug: unjs/unhead#278.

[harlan-zw]

The main issue is fixed upstream in Unhead 1.8.6.

There are a couple of interesting issues here:

1. There is a bug where an empty string for children will be converted to true, this is because it's inheriting the behavior of the attribute properties.
2. This is only a bug with children which is marked as deprecated, you should use innerHTML. The value for css is empty and it's still being provided to useHead, while this is valid it's not recommended. https://github.com/nuxt-modules/fontaine/blob/main/src/module.ts#L160

I'm going to fix #1 and will send a PR for #2 for tomorrow if you haven't done so before then

[danielroe]

I think this should be fixed in fontaine now 👍