The _checkpoint function won't be called for a user which is both a delegator and a delegatee in the increaseUnlockTime function

Lines of code Vulnerability details Impact The virtual balance of a user is calculated using 2 values - the amount that is delegated to that user, and his lock period. When calling the increaseUnlockTime function, we want to checkpoint the user's data as long as he doesn't have any funds. This is...