Removing Featured Image from Gutenberg post doesn't fully remove the featured media

[joshdarby]

Originally reported by CIJN: INN/umbrella-caribbean#87

When editing a Guternberg post that has featured media, removing the featured media via the Featured Image metabox doesn't actually remove the featured media meta. It still partially exists, causing a blank gray area with no image to appear on the post:

The template uses largo_hero
https://github.com/INN/largo/blob/1744bbc7ae99f501129d158c3b585cddf6b5409e/partials/content-single.php#L32

which then calls largo_get_hero
https://github.com/INN/largo/blob/512da701664b329f2f92244bbe54880a6e146431/inc/featured-media.php#L55-L83

which then uses largo_get_featured_hero
https://github.com/INN/largo/blob/512da701664b329f2f92244bbe54880a6e146431/inc/featured-media.php#L106-L160

which returns

string(38) "
"

Example output of largo_get_featured_media after removing the featured image:

array(3) { ["type"]=> string(5) "image" ["attachment"]=> int(15) ["attachment_data"]=> array(32) { ["id"]=> int(15) ["title"]=> string(17) "cijn-logo-profile" ["filename"]=> string(21) "cijn-logo-profile.png" ["url"]=> string(71) "https://caribbean.test/wp-content/uploads/2019/11/cijn-logo-profile.png" ["link"]=> string(40) "https://caribbean.test/?attachment_id=15" ["alt"]=> string(0) "" ["author"]=> string(1) "1" ["description"]=> string(0) "" ["caption"]=> string(0) "" ["name"]=> string(17) "cijn-logo-profile" ["status"]=> string(7) "inherit" ["uploadedTo"]=> int(0) ["date"]=> int(1574701219000) ["modified"]=> int(1574701219000) ["menuOrder"]=> int(0) ["mime"]=> string(9) "image/png" ["type"]=> string(5) "image" ["subtype"]=> string(3) "png" ["icon"]=> string(59) "https://caribbean.test/wp-includes/images/media/default.png" ["dateFormatted"]=> string(17) "November 25, 2019" ["nonces"]=> array(3) { ["update"]=> string(10) "5f154d902c" ["delete"]=> string(10) "3bb8c61661" ["edit"]=> string(10) "ccc3489447" } ["editLink"]=> string(60) "https://caribbean.test/wp-admin/post.php?post=15&action=edit" ["meta"]=> bool(false) ["authorName"]=> string(5) "admin" ["filesizeInBytes"]=> int(10145) ["filesizeHumanReadable"]=> string(5) "10 KB" ["context"]=> string(0) "" ["height"]=> int(400) ["width"]=> int(400) ["orientation"]=> string(9) "landscape" ["sizes"]=> array(3) { ["thumbnail"]=> array(4) { ["height"]=> int(140) ["width"]=> int(140) ["url"]=> string(79) "https://caribbean.test/wp-content/uploads/2019/11/cijn-logo-profile-140x140.png" ["orientation"]=> string(9) "landscape" } ["medium"]=> array(4) { ["height"]=> int(336) ["width"]=> int(336) ["url"]=> string(79) "https://caribbean.test/wp-content/uploads/2019/11/cijn-logo-profile-336x336.png" ["orientation"]=> string(9) "landscape" } ["full"]=> array(4) { ["url"]=> string(71) "https://caribbean.test/wp-content/uploads/2019/11/cijn-logo-profile.png" ["height"]=> int(400) ["width"]=> int(400) ["orientation"]=> string(9) "landscape" } }

Workaround:
Select Hide on Single Post display under Featured Media on a post that this is happening on to make the empty gray area not appear.