404 page title SEOmatic 404 page doesn't have a title. It shows "| Sitename" in my case.

I'm using Craft 3 with the SEOmatic plugin and would like to set the title in the 404 template.

{% set seomaticMeta = seomaticMeta | merge({ seoTitle: '404 page not found' }) %}


This gives a internal server error, looks like the seomaticMeta object is not available on the 404 page.
So it looks like you're using the old syntax for SEOmatic 1.x for Craft 2.x; here's how you do the same thing in SEOmatic for Craft 3:

{% do seomatic.meta.seoTitle("Some Title") %}


c.f.: https://github.com/nystudio107/craft-seomatic#twig-templating