adding fullscreen support for youtube embedded vids

src/Entity/Heartbeat.php

@@ -543,7 +543,7 @@ class Heartbeat extends RevisionableContentEntityBase implements HeartbeatInterf
       return '<' . $type . ' src="' . str_replace('public://', '/sites/default/files/', $filePath) . '" class="heartbeat-image" / >';
     } else if ($type == 'youtube') {
       $filePath = str_replace('youtube://', 'https://www.youtube.com/embed/', $filePath);
-      return '<iframe class="heartbeat-youtube" width="auto" height="auto" src="' . $filePath . '" frameborder="0"></iframe>';
+      return '<iframe class="heartbeat-youtube" width="auto" height="auto" src="' . $filePath . '" frameborder="0" allowfullscreen="allowfullscreen"></iframe>';
     } else if ($type == 'video') {
       return '<' . $type . ' controls src="' . str_replace('public://', '/sites/default/files/', $filePath) . '" class="heartbeat-video"></' . $type . '>';
     }
@@ -848,19 +848,19 @@ class Heartbeat extends RevisionableContentEntityBase implements HeartbeatInterf
 
   public static function flagAjaxBuilder($flagId, $entity, FlagService $flagService) {
 
-    $flag = $flagService->getFlagById($flagId);
-
-    $key = 'flag_' . $flag->id();
-    $data = [
-      '#lazy_builder' => ['flag.link_builder:build', [
-        $entity->getEntityTypeId(),
-        $entity->id(),
-        $flag->id(),
-      ]],
-      '#create_placeholder' => TRUE,
-    ];
-
-    return [$key => $data];
+    if ($flag = $flagService->getFlagById($flagId)) {
+      $key = 'flag_' . $flag->id();
+      $data = [
+        '#lazy_builder' => ['flag.link_builder:build', [
+          $entity->getEntityTypeId(),
+          $entity->id(),
+          $flag->id(),
+        ]],
+        '#create_placeholder' => TRUE,
+      ];
+      return [$key => $data];
+    }
+    return null;
   }
 
   /**