el problema es el siguiente java.lang.NullPointerException

Question

este es el problema que presento en android studio java.lang.RuntimeException: Unable to start activity ComponentInfo{com.blader.domicilios/com.blader.domicilios.activities.client.shopping_bag.ClientShoppingBagActivity}: java.lang.NullPointerException

en el cual cuando intento acceder a la bolsa de compras se me cierra la apliccion o se reinicia, lo mismo sucede cuando intento agregar otros productos y de la misma manera se cierra o se reinicia. necesito de su ayuda ya que estoy cortoo de tiempo para entregarla.

voy a poner el codigo de donde envia el error.

ClientShopingBagActivity

class ClientShoppingBagActivity : AppCompatActivity() {

var recyclerViewShoppingBag:  RecyclerView? = null
var textViewTotal: TextView? = null
var buttomNext: Button? = null
var toolbar: Toolbar? = null


var adapter: ShoppingBagAdapter? = null
var sharedPref: SharedPref? = null
var gson = Gson()
var selectedProducts = ArrayList<Product>()

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_client_shooping_bag)

    sharedPref = SharedPref((this))

    recyclerViewShoppingBag = findViewById(R.id.recyclerview_shopping_bag)
    textViewTotal = findViewById(R.id.textview_total)
    buttomNext = findViewById(R.id.btn_next)
    toolbar = findViewById(R.id.toolbar)
    toolbar?.setTitleTextColor(ContextCompat.getColor(this, R.color.white))
    toolbar?.title = "Tu orden"

    setSupportActionBar(toolbar)
    supportActionBar?.setDisplayHomeAsUpEnabled(true)

    recyclerViewShoppingBag?.layoutManager = LinearLayoutManager(this)

    getProductsFromSharedPref()
}

fun setTotal(total: Double){
    textViewTotal?.text = "${total}$"
}

private fun getProductsFromSharedPref(){
    if (!sharedPref?.getData("order").isNullOrBlank()){ //SI EXISTE UNA ORDEN EN SHARED PREFERENCE
        val type = object: TypeToken<ArrayList<Product>>(){}.type
        selectedProducts = gson.fromJson(sharedPref?.getData("order"), type)

        adapter = ShoppingBagAdapter(this, selectedProducts)
        recyclerViewShoppingBag?.adapter = adapter

    }
}

y este es el de ShoppingBagAdapter

class ShoppingBagAdapter(val context: Activity, val products: ArrayList): RecyclerView.Adapter<ShoppingBagAdapter.ShoppingBagViewHolder>() {

val sharedPref = SharedPref(context)


init {
    (context as ClientShoppingBagActivity).setTotal(getTotal())
}

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ShoppingBagViewHolder {
    val view = LayoutInflater.from(parent.context).inflate(R.layout.cardview_shopping_bag, parent, false)
    return ShoppingBagViewHolder(view)
}

override fun getItemCount(): Int {
    return products.size
}

override fun onBindViewHolder(holder: ShoppingBagViewHolder, position: Int) {

    val product = products[position] // CADA UNA DE LAS CATEGORIAS

    holder.textViewName.text = product.name
    holder.textViewCounter.text = "${product.quantity}"
    holder.textViewPrice.text = "${product.price * product.quantity!!}$"
    Glide.with(context).load(product.image1).into(holder.imageViewProduct)

    holder.imageViewAdd.setOnClickListener { addItem(product, holder) }
    holder.imageViewRemove.setOnClickListener { removeItem(product, holder) }
    holder.imageViewDelete.setOnClickListener { deleteItem(position) }

// holder.itemView.setOnClickListener { goToDetail(product) } }

private fun getTotal(): Double {
    var total = 0.0
    for (p in products) {
        total = total + (p.quantity!! * p.price)
    }
    return total
}

private fun getIndexOf(idProduct: String): Int {
    var pos = 0

    for (p in products) {
        if (p.id == idProduct) {
            return pos
        }
        pos++
    }

    return -1
}

private fun deleteItem(position: Int) {
    products.removeAt(position)
    notifyItemRemoved(position)
    notifyItemRangeRemoved(position, products.size)
    sharedPref.save("order", products)
    (context as ClientShoppingBagActivity).setTotal(getTotal())
}

private fun addItem(product: Product, holder: ShoppingBagViewHolder) {

    val index = getIndexOf(product.id!!)
    product.quantity = product.quantity!! + 1
    products[index].quantity = product.quantity

    holder.textViewCounter.text = "${product.quantity}"
    holder.textViewPrice.text = "${product.quantity!! * product.price}$"

    sharedPref.save("order", products)
    (context as ClientShoppingBagActivity).setTotal(getTotal())
}

private fun removeItem(product: Product, holder: ShoppingBagViewHolder) {

    if (product.quantity!! > 1) {

        val index = getIndexOf(product.id!!)
        product.quantity = product.quantity!! - 1
        products[index].quantity = product.quantity

        holder.textViewCounter.text = "${product.quantity}"
        holder.textViewPrice.text = "${product.quantity!! * product.price}$"

        sharedPref.save("order", products)
        (context as ClientShoppingBagActivity).setTotal(getTotal())

    }

}

private fun goToDetail(product: Product) {
    val i = Intent(context, ClientProductsDetailActivity::class.java)
    i.putExtra("product", product.toJson())
    context.startActivity(i)
}

class ShoppingBagViewHolder(view: View): RecyclerView.ViewHolder(view) {

    val textViewName: TextView
    val textViewPrice: TextView
    val textViewCounter: TextView
    val imageViewProduct: ImageView
    val imageViewAdd: ImageView
    val imageViewRemove: ImageView
    val imageViewDelete: ImageView

    init {
        textViewName = view.findViewById(R.id.textview_name)
        textViewPrice = view.findViewById(R.id.textview_price)
        textViewCounter = view.findViewById(R.id.textview_counter)
        imageViewProduct = view.findViewById(R.id.imageview_product)
        imageViewAdd = view.findViewById(R.id.imageview_add)
        imageViewRemove = view.findViewById(R.id.imageview_remove)
        imageViewDelete = view.findViewById(R.id.imageview_delete)
    }

}