Use EXTCODEHASH instead of EXTCODESIZE

Author: duncancmt

Diff for: src/deployer/Deployer.sol

@@ -105,7 +105,10 @@ contract Deployer is TwoStepOwnable {
             mstore(add(ptr, initCode.length), _feeCollector)
             deployed := create(callvalue(), ptr, add(initCode.length, 0x20))
         }
-        if (deployed == address(0) || deployed.code.length == 0) {
+        if (
+            deployed == address(0)
+                || deployed.codehash == 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470
+        ) {
             revert DeployFailed();
         }
         emit Deployed(newNonce, deployed);
@@ -133,7 +136,10 @@ contract Deployer is TwoStepOwnable {
         unchecked {
             for (uint64 i = nonce; i != 0; --i) {
                 address instance = AddressDerivation.deriveContract(address(this), i);
-                if (!isUnsafe[instance] && instance.code.length > 0) {
+                if (
+                    !isUnsafe[instance]
+                        && instance.codehash != 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470
+                ) {
                     return instance;
                 }
             }