Redux Toolkit 1.9.3 and 'Property 'push' does not exist on type 'WritableDraft<CartState>'

Trying out ReduxToolkit with TypeScript and I'm stumped on something that I suspect is really simple / obvious. However, I don't know enough to figure it out and need some guidance.

Basically I get a Property 'push' does not exist on type 'WritableDraft'. error in the following code:

import { createSlice, PayloadAction } from '@reduxjs/toolkit'
import { Product } from '../pages/Product/Types'

export interface CartState {
  products: Product[]
}

const initialState: CartState = {
  products: []
}

export const cartSlice = createSlice({
  name: 'cart',
  initialState,
  reducers: {
    addToCart: (state, action: PayloadAction<Product>) => {
      state.push(action.payload) <=== ERROR HERE, WITH 'push'
    }
  }
})

// Action creators are generated for each case reducer function
// export const { addToCart, decrement, incrementByAmount } = cartSlice.actions
export const { addToCart } = cartSlice.actions

export default cartSlice.reducer

I understand that push() isn't working because state isn't considered an array, but I don't see how to fix that, given what code is already here. Any help is appreciated; thanks!

Your cart state has a products field that you are missing:

export const cartSlice = createSlice({
  name: 'cart',
  initialState,
  reducers: {
    addToCart: (state, action: PayloadAction<Product>) => {
      state.products.push(action.payload)
//          ~~~~~~~~
    }
  }
})

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