Passing arguments to base constructor fails

I have a Character class with a ragdoll and a HumanoidCharacter subclass that should set it.

 public class Character : MonoBehaviour {
     private Ragdoll ragdoll;
     
     public Character(Ragdoll ragdoll, int maxInventorySize) {
         if (ragdoll == null) throw new System.ArgumentNullException("ragdoll");
         this.ragdoll = ragdoll;
     }
 }

 public class HumanoidCharacter : Character {
     public HumanoidCharacter(int maxInventorySize) : base(new Ragdoll(new ItemSlot[] {new ItemSlot(ItemSlotType.RightHand)}), maxInventorySize) {
 }
 }

 public class PlayerCharacter : HumanoidCharacter {
     public PlayerCharacter() : base(32) {
     }
 }

I'm getting the ArgumentNullException for ragdoll when I attach PlayerCharacter to a GameObject.

I would have thought that PlayerCharacter's constructor is called, which calls HumanoidCharacter's sonstructor which then calls Character's constructor with the new Ragdoll. What's going wrong?