Hreflang tag shouldn't be outputted when a translation is connected but unpublished

[nowori]

Hey there,

Currently, MSLS outputs the homepage URL for hreflang tags, when a page is connected but not published. This seems to be bad practice, which makes sense as hreflang tags are supposed to be reciprocal, that is they should all reference each other on their respective page, which doesn't happen when we output the homepage hreflang on a specific page = it wouldn't be reciprocated on the homepage.

Difficult to find references on the topic but here are some:
https://webmasters.stackexchange.com/questions/118439/use-of-rel-alternate-on-multilingual-site/118455
https://cognitiveseo.com/blog/17150/multi-language-website-mistakes/

I am not proposing a pull request as I'm unsure how to best cater for this.

It seems that the goal of this code was to implement this scenario:

Multisite-Language-Switcher/includes/MslsOutput.php

Lines 110 to 112 in d5747af

	if ( is_null( $url ) ) {
	continue;
	}

But it seems it is never null because of:

Multisite-Language-Switcher/includes/MslsOptions.php

Line 233 in d5747af

return '' != $postlink ? $postlink : home_url( '/' );

But I guess this is not where this should be fixed as it is probably used to output the language switcher, amongst other things. Would appreciate if you could have a look.

For now and if others want to fix this behavior, this is how I've implemented it:

add_filter( 'mlsl_output_get_alternate_links', function( $url, $blog ) {

	if ( !is_front_page() && $url === trailingslashit( $blog->siteurl ) )
		return null;
	else
		return $url;

}, 10, 2 );

Thank you