EVM: Fix smart accounts handler

packages/evm/contracts/smart-accounts/SmartAccountsHandler.sol

@@ -16,13 +16,16 @@ pragma solidity ^0.8.20;
 
 import '@openzeppelin/contracts/token/ERC20/IERC20.sol';
 import '@openzeppelin/contracts/utils/Address.sol';
+import '@openzeppelin/contracts/utils/introspection/ERC165Checker.sol';
 
 import '../interfaces/ISafe.sol';
 import '../interfaces/ISmartAccount.sol';
 import '../interfaces/ISmartAccountsHandler.sol';
 import '../utils/Denominations.sol';
 
 contract SmartAccountsHandler is ISmartAccountsHandler {
+    using ERC165Checker for address;
+
     /**
      * @dev Tells whether an account is a supported smart account
      * @param account Address of the account being queried
@@ -90,22 +93,15 @@ contract SmartAccountsHandler is ISmartAccountsHandler {
      * @param account Address of the account being queried
      */
     function _isMimicSmartAccount(address account) internal view returns (bool) {
-        try ISmartAccount(account).supportsInterface(type(ISmartAccount).interfaceId) returns (bool ok) {
-            return ok;
-        } catch {
-            return false;
-        }
+        return account.supportsInterface(type(ISmartAccount).interfaceId);
     }
 
     /**
      * @dev Tells whether an account is a Gnosis Safe
      * @param account Address of the account being queried
      */
     function _isSafe(address account) internal view returns (bool) {
-        try ISafe(account).getThreshold() returns (uint256) {
-            return true;
-        } catch {
-            return false;
-        }
+        (bool success, bytes memory data) = account.staticcall(abi.encodeWithSelector(ISafe.getThreshold.selector));
+        return success && data.length == 32;
     }
 }

packages/evm/contracts/test/smart-accounts/FallbackMock.sol

@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.20;
+
+contract FallbackMock {
+    fallback() external payable {}
+
+    receive() external payable {}
+}

packages/evm/test/smart-accounts/SmartAccountsHandler.test.ts

@@ -45,6 +45,12 @@ describe('SmartAccountsHandler', () => {
       expect(await handler.isSmartAccount(handler)).to.be.false
     })
 
+    it('returns false for contracts with a fallback only', async () => {
+      const fallback = await ethers.deployContract('FallbackMock')
+
+      expect(await handler.isSmartAccount(fallback)).to.be.false
+    })
+
     it('returns true for a Mimic SmartAccount', async () => {
       expect(await handler.isSmartAccount(smartAccountContract)).to.be.true
     })