Follower Model: Fall back to post-meta (#1781)

Co-authored-by: Automattic Bot <[email protected]>

Author: pfefferle

.github/changelog/1781-from-description

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fixed
+
+Added fallback for follower list during migration to new database schema.

includes/model/class-follower.php

@@ -364,8 +364,14 @@ public function get_shared_inbox() {
 	 * @return Follower|false The Follower object or false on failure.
 	 */
 	public static function init_from_cpt( $post ) {
+		if ( empty( $post->post_content ) ) {
+			$json = \get_post_meta( $post->ID, '_activitypub_actor_json', true );
+		} else {
+			$json = $post->post_content;
+		}
+
 		/* @var Follower $object Follower object. */
-		$object = self::init_from_json( $post->post_content );
+		$object = self::init_from_json( $json );
 
 		if ( is_wp_error( $object ) ) {
 			return false;