problem configuring mollie payment
It looks like either 'Asset Account is' account relationship is deleted or disabled. You can check by navigation to CiviCRM >> Administer >> System Settings >> Option Groups. Find for 'Account Relationship' option, click 'edit option' link besides it. Find for 'Asset Account is' if its disabled or deleted.

Solution: 


If disabled then enable it using api or through sql.
If deleted then Add a new one with Label and Name as 'Asset Account is'.


Cheers

Pradeep