Adding an if check to avoid unnecessary call

[code423n4]

Handle

0xngndev

Vulnerability details

Impact

In the contract NestedBuybacker, the internal function trigger calculates how much NST to send to the reserve by doing:
uint256 toSendToReserve = balance - toBurn;
and then makes a safeTransfer for that amount to the nstReserve contract:
NST.safeTransfer(nstReserve, toSendToReserve);
Because there's a possibility of the burn rate set to 100%, there can exist situations where the contract ends up transferring 0 NST to the reserve. This would incur in unnecessary gas costs that can be avoided with a simple if check.
The if check increases the contract size from 6189 to 6195 bytes, and adds a small amount of gas cost. However, if the possibility of having the burn rate set to 100% is something feasible, avoiding that call should
end up being cheaper than adding an if check.

Mitigation steps

Simply add an if check to the NST.safeTransfer line that checks that toSendToReserve is not 0

[adrien-supizet]

This is true. Although we are not considering to set the the burn part to 100%.