Quantity.cs

public record Quantity
{
    private int Value { get; }

    public Quantity(int value)
    {
        if (value <= 0)
        {
            throw new InvalidOperationException("Quantity must be greater than zero.");
        }

        Value = value;
    }

    public static implicit operator int(Quantity quantity) => quantity.Value;
}

Shouldn't the condition on line 7 be value <= 0 instead of value >= 0?