Ensure consistent return type in WP_Navigation_Block_Renderer::get_markup_for_inner_block()

[afragen]

Fixes get_markup_for_inner_block()

What?

moves return outside of conditional so method can return '' instead of null.

Why?

Fixes #59814 and https://core.trac.wordpress.org/ticket/60762

How?

move return outside of conditional

Testing Instructions

An empty inner_block on a site triggers this error

Testing Instructions for Keyboard

Screenshots or screencast

[github-actions]

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Co-authored-by: afragen <afragen@git.wordpress.org>
Co-authored-by: swissspidy <swissspidy@git.wordpress.org>
Co-authored-by: getdave <get_dave@git.wordpress.org>

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[afragen]

$inner_block_content starts out as an empty string. It shouldn’t need to be set to an empty string before the return. The only reason the current code returns null when the value is empty ('') is that the variable is not returned from inside the conditional. The method simply exits. $inner_block->render() returns ''. All that really needs to happen to return '' is to move the return outside of the conditional.

FWIW, I have tested this locally and it does fix the issue.

[getdave]

Should be in Gutenberg repo.

Update: all good. I saw this, got confused, and scrambled to avoid a commit going into the wrong repo. Turns out it is in the right repo 😄

My mistake !

[getdave]

This bug was identified during the RC period for WP 6.5. It represents potential for an error in the Navigation block and therefore should be included in WP 6.5.

[youknowriad]

I just cherry-picked this PR to the update/packages-rc2-6.5 branch to get it included in the next release: ad56431