wp_get_document_title() and post type archives by author

[greenshady]

Previously, wp_title() ran a check when is_author() like so:

if ( is_author() && ! is_post_type_archive() ) {
	$author = get_queried_object();
	if ( $author ) {
		$title = $author->display_name;
	}
}

This made sense when viewing a post type archive by author like example.com/?post_type=post_type&author=author_nicename.

However, wp_get_document_title() doesn't check this:

} elseif ( is_author() && $author = get_queried_object() ) {
	$title['title'] = $author->display_name;

The following notice is now given on post type archives by author:

Notice: Undefined property: stdClass::$display_name in C:\xampp\htdocs\wp-includes\general-template.php on line 875

This is because the queried object is actually the post type object rather than the author/user object.

[greenshady]

Note that this was fixed for wp_title() in [28251].

[obenland]

In 35700:

Template: Get the author name directly from $authordata.

Since [25574] $authordata gets set up in WP::register_globals() - no need
to take a detour over the queried object.

Props greenshady for initial patch.
Fixes #34516.

[ocean90]

@obenland: $authordata doesn't get set up if $wp_query->post is empty, means empty author archives will have an empty 'title' part.

[obenland]

34516.2.diff​ reverts [35700] and reorders template checks to be in line with WP_Query::get_queried_object().

At some point we should double-check and update get_body_class(), get_the_archive_title() etc.

[obenland]

In 35706:

Template: Use template-loader.php as cononical source of truth for conditional ordering.

Reverts [35700] which didn't account for author archives without posts.
Determination of the correct title is now based on the same order of
conditionals that template loader uses to select the right template.

H/t ocean90.
Fixes #34516.