Lots of the contracts in this project import import "@openzeppelin/contracts-upgradeable/utils/AddressUpgradeable.sol" and use address.isContract() to check if an address is a contract and not a EOA. I guess this is only a check if the deployer by mistake provides the wrong address. I think this should be double-checked off-chain. If an on-chain check is needed, there are other checks that can be done that are even more strict than just checking against EOA mistakes. For example, we can provide the contract as the second input to the constructor and check the addresss codehash against that. Here is a template as an example:
Not only does this check for address with code, but also pinpoints the contract hash to a specific hash. Another type of check that can be used is to check if the provided contract address supports a specific interfaceSupport or call an endpoint of the contract expecting it to return a specific magic number.
Here is a list of places isContract has been used:
