Irreversible Errors in model with circular calculation

I have a bit complicated financial model used to forecast futures years' P&L performance, balance sheet and cash flow. It has circular calculation each year and each year's result will be used to calculate the following year.

It works but whenever I inadvertently input or delete any value that returns #Div/0! or #REF! then press F9 to calculate, all the out years calculation has error messages. Even I undo what I did, it seems the errors message are irreversible and the loaded model is screwed.

I guess my first question is why you built it to allow or even need circular calculation. It's very difficult to get the results right even when allowing it because Excel only goes through x many iterations. Do you have the option for allowing circular references checked or unchecked? I assume checked, but it doesn't hurt to ask.

Also, would it be possible to post the workbook with dummy data?