Iterating through children causes InvalidCastException

Hello, I want to make a dynamic shop UI, but when changing the category I want to, obviously, clear whatever was previously in it. So I am iterating through all children, which for some reason causes an InvalidCastException. I have used the same loop in a different part of my code, but there it doesn't throw the exception.

Code:

 public void LoadForCategory(BuildingCategory category)
     {
         foreach(GameObject child in this.transform) // This is line 12 where the error occurs.
         {
             Destroy(child);
         }
 
         List<Building> buildings = new List<Building>();
 
         if(category == BuildingCategory.DECORATION)
         {
             buildings = BuildingsRegistry.self.FilterByCategories(new BuildingCategory[] { BuildingCategory.DECORATION });
         }
 
         foreach(Building building in buildings)
         {
             GameObject newButton = Instantiate(buildingItemPrefab);
             newButton.transform.Find("PriceText").GetComponent<Text>().text = "$ " + building.price;
             newButton.transform.Find("PreviewImage").GetComponent<Image>().sprite = building.preview;
             newButton.transform.parent = transform;
         }
     }

The error:

 InvalidCastException: Specified cast is not valid.
 BuildingItemList.LoadForCategory (BuildingCategory category) (at Assets/Scripts/Mechanics/Building/UI/BuildingItemList.cs:12)
 BuildingCategoryButton.OnClick () (at Assets/Scripts/Mechanics/Building/UI/BuildingCategoryButton.cs:12)
 UnityEngine.Events.InvokableCall.Invoke () (at <f98083cbc97e4fa0a4ef2f523feff5e1>:0)
 UnityEngine.Events.UnityEvent.Invoke () (at <f98083cbc97e4fa0a4ef2f523feff5e1>:0)