1 - Check zero address implementation before the "acceptUpgrade" function.
It would worth to check the zero address implementation before the acceptUpgrade function, so the acceptUpgrade function would already have a non-zero implementation.
The zero address check could be in the updgradeTo function and that function could be used in the constructor, so the constructor also can check the non-zero implementation.
1 - Check zero address implementation before the "acceptUpgrade" function.
It would worth to check the zero address implementation before the acceptUpgrade function, so the
acceptUpgradefunction would already have a non-zero implementation.The zero address check could be in the updgradeTo function and that function could be used in the constructor, so the
constructoralso can check the non-zero implementation.Links: