Fix possible null values or not null values in some entity / string properties

src/Bundle/ChillPersonBundle/Entity/AccompanyingPeriod/Comment.php

@@ -49,7 +49,7 @@ class Comment implements TrackCreationInterface, TrackUpdateInterface
      *
      * @Assert\NotNull
      */
-    private ?string $content = null;
+    private string $content = '';
 
     /**
      * @ORM\Column(type="datetime")
@@ -99,7 +99,7 @@ class Comment implements TrackCreationInterface, TrackUpdateInterface
         return $this->accompanyingPeriod;
     }
 
-    public function getContent(): ?string
+    public function getContent(): string
     {
         return $this->content;
     }