Transaction failed due to insufficient gas fees

When I try to swap 100% of my TZERO there is no warning shown upfront. Because there probably is insufficient funds for gas the transaction fails. After I approve the transaction in my wallet an error message is shown: Transaction failed

As a user who wants to swap all of his TZERO I want to know that I can't swap 100% of my TZERO before I press the SWAP button (for example by notifcation message "Insufficient funds for gas") OR the gas fees are deducted automatically from the 100% swap amount.