Let SocialAction::defaultNotificationDelay be nullable.

src/Bundle/ChillPersonBundle/Entity/SocialWork/SocialAction.php

@@ -47,7 +47,7 @@ class SocialAction
     private $children;
 
     /**
-     * @ORM\Column(type="dateinterval")
+     * @ORM\Column(type="dateinterval", nullable=true)
      */
     private $defaultNotificationDelay;
 

src/Bundle/ChillPersonBundle/migrations/Version20210623142046.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Chill\Migrations\Person;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+/**
+ * Auto-generated Migration: Please modify to your needs!
+ */
+final class Version20210623142046 extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return '';
+    }
+
+    public function up(Schema $schema): void
+    {
+        $this->addSql('ALTER TABLE chill_person_social_action ALTER defaultnotificationdelay DROP NOT NULL');
+    }
+
+    public function down(Schema $schema): void
+    {
+        $this->addSql('ALTER TABLE chill_person_social_action ALTER defaultNotificationDelay SET NOT NULL');
+    }
+}