Change reactions column to nullable with default null

database/migrations/2026_04_15_000001_create_post_comments_table.php

@@ -16,7 +16,7 @@ public function up(): void
             $table->uuid('user_id')->nullable();
             $table->uuid('parent_id')->nullable();
             $table->text('body');
-            $table->json('reactions')->default('[]');
+            $table->json('reactions')->nullable()->default(null);
             $table->timestamps();
 
             $table->foreign('post_id')->references('id')->on('posts')->cascadeOnDelete();