Preview not showing the page properly

[saleemhaq]

Below is the preview setting of page:

when i come on edit mode:

and click preview:

it showing the blank page because in that content type I used list and list populate data by its .cs file so it cause the null issue, how can i handle that please advise?

instead of proper working page like when click on view it showing the page correctly:

Please advise i need to display proper in preview like view click?