fix return types of transformer functions

includes/activitypub/transformer/class-events-manager.php

@@ -125,14 +125,14 @@ final class Events_Manager extends Event_Transformer {
 	/**
 	 * Get the end time from the events metadata.
 	 */
-	public function get_end_time() {
+	public function get_end_time(): ?string {
 		return null;
 	}
 
 	/**
 	 * Get the end time from the events metadata.
 	 */
-	public function get_start_time() {
+	public function get_start_time(): string {
 		$date_string     = $this->em_event->event_start_date;
 		$time_string     = $this->em_event->event_start_time;
 		$timezone_string = $this->em_event->event_timezone;

includes/activitypub/transformer/class-gatherpress.php

@@ -97,14 +97,14 @@ final class GatherPress extends Event {
 	/**
 	 * Get the end time from the event object.
 	 */
-	protected function get_end_time() {
+	protected function get_end_time(): ?string {
 		return $this->gp_event->get_datetime_end( 'Y-m-d\TH:i:s\Z' );
 	}
 
 	/**
 	 * Get the end time from the event object.
 	 */
-	protected function get_start_time() {
+	protected function get_start_time(): string {
 		return $this->gp_event->get_datetime_start( 'Y-m-d\TH:i:s\Z' );
 	}
 

includes/activitypub/transformer/class-the-events-calendar.php

@@ -64,7 +64,10 @@ final class The_Events_Calendar extends Event {
 	/**
 	 * Get the end time from the event object.
 	 */
-	protected function get_end_time() {
+	protected function get_end_time(): ?string {
+		if ( empty( $this->tribe_event->end_date ) ) {
+			return null;
+		}
 		$date = date_create( $this->tribe_event->end_date, wp_timezone() );
 		return \gmdate( 'Y-m-d\TH:i:s\Z', $date->getTimestamp() );
 	}
@@ -72,7 +75,7 @@ final class The_Events_Calendar extends Event {
 	/**
 	 * Get the end time from the event object.
 	 */
-	protected function get_start_time() {
+	protected function get_start_time(): string {
 		$date = date_create( $this->tribe_event->start_date, wp_timezone() );
 		return \gmdate( 'Y-m-d\TH:i:s\Z', $date->getTimestamp() );
 	}