Why is my Typescript strong typing not working?

I have the following model:

export class ProductModel {    
    _id: string = '';
    brand: string = '';
    description: string = '';
    images: string[] = [];
    price: number = 0;
    discount: number = 0;
    rating: number = 0;
    category: string = '';
    attributes: {} = {};
    specifications: string[] = [];
    productCount:number = 0;
}

My ngrx reducer uses the above model:

const initialState = {
    products: ProductModel[] = [], 
    productCount: 0
}

// const initialState = new ProductModel();

export const ProductReducer = createReducer(
    initialState,

    on(StoreProducts, (state, action) => {
        console.log('ProductReducer.StoreProducts.products', action.productData)
      return {
        ...state,
        products: action.productData.products,
        productCount: action.productData.productCount,        
      };
    }),
)

I get the following error about this declaration products: ProductModel[] = [], in the initialState. The error says:

Element implicitly has an 'any' type because expression of type 'any' can't be used to index type 'typeof ProductModel'.ts(7053) An element access expression should take an argument.ts(1011)

Your syntax of the object literal is wrong, you're trying to assign a type [] to ProductModel[] as the default value or something like that and not providing a proper object literal.

Use some proper form like:

const initialState: {products: ProductModel[], productCount: number} = {
  products: [], 
  productCount: 0
} 

const initialState2 = {
  products: [] as ProductModel[], 
  productCount: 0
} 

const initialState3 = new class {
  products: ProductModel[] = [];
  productCount = 0
}