Why does my script keep getting a RuntimeError?

[KenG48]

Hi everyone, firstly having read so many posts on here regarding scripts etc it's great to see the help you guys all give so Thank you, you have already helped me with other issues which I have resolved!!!

Unfortunately, I haven't been able to find my solution, hence this post.

I have "inherited" a script and it seems that I keep getting a run time error, mainly when the site gets really busy (could just be coincidence).

The error points to the line starting "when CartDiscount::Percentage" but I assume this is the start of this particular block of code?

My gut tells me it's the line below "Input.cart.subtotal_price * ((Decimal.new(100) - Input.cart.discount_code.percentage) / 100) "  but I don't understand Ruby that well.

The error message is "Message: new line_price must be lower than the current line_price"

  cart_discounted_subtotal = 
  case Input.cart.discount_code
  when CartDiscount::Percentage
    if Input.cart.discount_code.code.start_with? 'XX' or Input.cart.discount_code.code.start_with? 'spec-' 
      Input.cart.subtotal_price
    elsif Input.cart.subtotal_price >= Input.cart.discount_code.minimum_order_amount
      Input.cart.subtotal_price * ((Decimal.new(100) - Input.cart.discount_code.percentage) / 100) 
    else
      Input.cart.subtotal_price
    end
  when CartDiscount::FixedAmount
    if Input.cart.subtotal_price >= Input.cart.discount_code.minimum_order_amount
      [Input.cart.subtotal_price - Input.cart.discount_code.amount, Money.zero].max
    else
      Input.cart.subtotal_price
    end
  else
    Input.cart.subtotal_price
  end