Cannot access ‘usagePrice’ before initialization

I have a script that I’m using to calculate the price of a selected field

When i run the function ‘calculateTotal()’ i get this error “Cannot access ‘usagePrice’ before initialization”.

Here is my code:

// Returns total for step 1
const usagePrice = () => {
    const field = document.querySelector('input[name="usage"]:checked');
    const subField = document.querySelector('input[name="varifocal-lenses"]:checked');

    let price = field.dataset.price;
       

    if (field.value == 'varifocal') {
        
        price = subField.dataset.price;
    }

    console.log('Usage price: ' + price);
    return price;
}

// Adds all totals together
const calculateTotal = () => {
    const usagePrice = usagePrice();
    const prescriptionPrice = prescriptionPrice();
    const lensPackagePrice = lensPackagePrice();
    const lensTypePrice = lensTypePrice();

    const total = usagePrice + prescriptionPrice + lensPackagePrice + lensTypePrice;

    return total;
}


console.log(calculateTotal());

Can anyone explain whats going wrong? Thank you in advance.