Issue #3281327: Fallback image if the image is not found

src/Plugin/ProjectBrowserSource/RandomDataPlugin.php

@@ -183,7 +183,7 @@ class RandomDataPlugin extends PluginBase implements ProjectBrowserSourceInterfa
         'field_project_images' => [
           [
             'file' => [
-              'uri' => 'https://picsum.photos/600/400',
+              'uri' => rand(0, 3) ? 'https://picsum.photos/600/400' : 'https://image.not/found.jpg',
               'resource' => 'image',
             ],
             'alt' => $machine_name . ' logo',