Fix lesson translation for the course outline (#7496)

* Fix an issue with using an object as array
* Update lesson relations for existing lessons as well

includes/wpml/class-sensei-wpml.php

@@ -285,13 +285,13 @@ public function update_lesson_properties_on_course_translation_created( $new_cou
 			if ( ! $is_translated ) {
 				// phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound
 				do_action( 'wpml_admin_make_post_duplicates', $lesson_id );
+			}
 
-				// phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound
-				$translations = apply_filters( 'wpml_post_duplicates', $lesson_id );
-				foreach ( $translations as $translated_lesson_id ) {
-					$this->update_lesson_course( (int) $translated_lesson_id, $new_course_id );
-					$this->update_translated_lesson_taxonomies( (int) $translated_lesson_id, $lesson_id );
-				}
+			// phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound
+			$translations = apply_filters( 'wpml_post_duplicates', $lesson_id );
+			foreach ( $translations as $translated_lesson_id ) {
+				$this->update_lesson_course( (int) $translated_lesson_id, $new_course_id );
+				$this->update_translated_lesson_taxonomies( (int) $translated_lesson_id, $lesson_id );
 			}
 
 			// Sync lesson course field across translations.
@@ -348,6 +348,7 @@ private function update_translated_lesson_taxonomies( $new_lesson_id, $master_le
 			return;
 		}
 
+		$details = (array) $details;
 		if ( empty( $master_lesson_id ) ) {
 			if ( empty( $details['source_language_code'] ) ) {
 				return;