I was testing something else and did not enter a payout amount, which resulted in an error 500. I think it should result in a warning or error message to tell the staff member that they forgot to enter a value in the payout input. To recreate: 1. Go to a patron account > Accounting 2. Click 'Create manual invoice' 3. Enter an amount 4. Click 'Save and pay' 5. Click 'Confirm' 6. Click 'Transactions' 7. Click 'Payout amount' (should the button even appear if the patron has 0 due?) 8. Click 'Confirm' It should say something like "Please enter a payout amount".