Gas Optimizations

[code423n4]

[G - 01] Useless nonReentrant keyword

Here, in withdraw, the nonReentrant keyword is useless as the vault is burn line 335 before any external call, any reentrant call would fail because of the require line 323 as the owner would be the 0 address. Overall, ReentrancyGuard inheritance can be removed.

[G - 02] In CallyNFT, override transferFrom

Although the transfer functions of CallyNFT won’t revert because arithmetics are unchecked (see code), the contracts should still override transferFrom to remove the modifications of _balanceOf . First out of coherence and then for gas savings. You could also remove the _balanceOf mapping as it becomes useless. Note that this does not concern the Cally contract which does override transferFrom but only for other contracts that may use CallyNFT.