fix(Gateway setup): check admins/owners/operators for address(0) (#84)

* fix(Gateway setup): check admins/owners/operators for address(0)

* chore(npm): version bump

* refactor(Gateway): emptiness emphasizes the contents

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@axelar-network/axelar-cgp-solidity",
-  "version": "3.1.0",
+  "version": "3.1.1",
   "description": "Ethereum Smart Contracts for Axelar Network",
   "main": "index.js",
   "scripts": {

src/AdminMultisigBase.sol

@@ -161,6 +161,8 @@ contract AdminMultisigBase is EternalStorage {
             // Check that the account wasn't already set as an admin for this epoch.
             if (_isAdmin(adminEpoch, account)) revert DuplicateAdmin(account);
 
+            if (account == address(0)) revert InvalidAdmins();
+
             // Set this account as the i-th admin in this epoch (needed to we can clear topic votes in `onlyAdmin`).
             _setAdmin(adminEpoch, i, account);
             _setIsAdmin(adminEpoch, account, true);

src/AxelarGatewayMultisig.sol

@@ -184,6 +184,8 @@ contract AxelarGatewayMultisig is IAxelarGatewayMultisig, AxelarGateway {
             // Check that the account wasn't already set as an owner for this ownerEpoch.
             if (_isOwner(epoch, account)) revert DuplicateOwner(account);
 
+            if (account == address(0)) revert InvalidOwners();
+
             // Set this account as the i-th owner in this ownerEpoch (needed to we can get all the owners for `owners`).
             _setOwner(epoch, i, account);
             _setIsOwner(epoch, account, true);
@@ -335,7 +337,7 @@ contract AxelarGatewayMultisig is IAxelarGatewayMultisig, AxelarGateway {
             // Check that the account wasn't already set as an operator for this operatorEpoch.
             if (_isOperator(epoch, account)) revert DuplicateOperator(account);
 
-            if (account == address(0)) revert InvalidAddress();
+            if (account == address(0)) revert InvalidOperators();
 
             // Set this account as the i-th operator in this operatorEpoch (needed to we can get all the operators for `operators`).
             _setOperator(epoch, i, account);