chore(multi-treasury): merge from release/v0.3.5 (#241)

src/RONRegistrarController.sol

@@ -92,8 +92,8 @@ contract RONRegistrarController is
     _setPriceOracle(priceOracle);
     _setMinRegistrationDuration(minRegistrationDuration);
     _setCommitmentAge(minCommitmentAge, maxCommitmentAge);
+    _setTreasury(treasury);
 
-    _treasury = treasury;
     _rnsUnified = rnsUnified;
     _nameChecker = nameChecker;
     _reverseRegistrar = reverseRegistrar;
@@ -281,7 +281,7 @@ contract RONRegistrarController is
    * @inheritdoc IRONRegistrarController
    */
   function setTreasury(address payable addr) external onlyRole(DEFAULT_ADMIN_ROLE) {
-    _treasury = addr;
+    _setTreasury(addr);
   }
 
   /**
@@ -452,6 +452,19 @@ contract RONRegistrarController is
     emit DomainPriceUpdated(_msgSender(), priceOracle);
   }
 
+  /**
+   * @dev Helper method to update treasury address.
+   *
+   * Emits an event {TreasuryUpdated}.
+   */
+  function _setTreasury(address payable addr) internal {
+    if (addr == address(0x0)) revert NullAddress();
+
+    _treasury = addr;
+
+    emit TreasuryUpdated(addr);
+  }
+
   /**
    * @dev Helper method to check if a domain name is available for register.
    */

src/interfaces/IRONRegistrarController.sol

@@ -38,6 +38,8 @@ interface IRONRegistrarController {
   error ErrInvalidRegisterProtectedName(string name, address requestOwner, bool nameProtected, bool ownerWhitelisted);
   /// @dev Thrown when received invalid array length
   error InvalidArrayLength();
+  /// @dev Thrown when treasury address is set to null
+  error NullAddress();
 
   /**
    * @dev Emitted when the min registration duration is updated.
@@ -46,6 +48,9 @@ interface IRONRegistrarController {
    */
   event MinRegistrationDurationUpdated(address indexed operator, uint256 duration);
 
+  /// @dev Emitted when the treasury is updated.
+  event TreasuryUpdated(address indexed addr);
+
   /**
    * @dev Emitted when RNSDomainPrice contract is updated.
    * @param operator The address of the operator who triggered the update.