Custom editor struggle - "Invalid iteration - (You need to stop calling Next when it returns false)"

Been struggling a lot lately with custom editors and drawers. It seems like Unity doesn't give in easily, but yet insist on having a static non-resilient brain.

I got this error when I passed a a SerializedProperty of a Vector3 value, into a EditorGUILayout.PropertyField

 public abstract class FancyList : MonoBehaviour { }
 
 public class FunnyLookingList : FancyList
 {
     [SerializeField] [HideInInspector]
     private List<Vector3> list;
 }

 [CustomEditor(typeof(FancyList), true)]
 public class FancyEditor : Editor
 {
     private SerializedProperty list;
     private void OnEnable()
     {
         list = serializedObject.FindProperty("list");
     }
     public override void OnInspectorGUI()
     {
         DrawDefaultInspector();
         list.Add(new Vector3(1, 1, 1));
         EditorGUILayout.PropertyField(list.GetAt(0)); // <--
     }
 }

Where:

 public static void Add(this SerializedProperty prop, Vector3 v)
 {
     prop.arraySize++;
     prop.GetAt(prop.arraySize - 1).vector3Value = v;
 }

 public static SerializedProperty GetAt(this SerializedProperty prop, int i)
 {
     return prop.GetArrayElementAtIndex(i);
 }

Any ideas?

Thanks.