fix(KC): check safeTransfer for withdrawLeftover

Author: unknownunknown1

contracts/src/arbitration/KlerosCore.sol

@@ -632,7 +632,7 @@ contract KlerosCore is IArbitratorV2, Initializable, UUPSProxiable {
     function transferBySortitionModule(address _account, uint256 _amount) external {
         if (msg.sender != address(sortitionModule)) revert SortitionModuleOnly();
         // Note eligibility is checked in SortitionModule.
-        pinakion.safeTransfer(_account, _amount);
+        if (!pinakion.safeTransfer(_account, _amount)) revert TransferFailed();
     }
 
     /// @inheritdoc IArbitratorV2

contracts/test/foundry/KlerosCore_Execution.t.sol

@@ -487,6 +487,15 @@ contract KlerosCore_ExecutionTest is KlerosCore_TestBase {
         assertEq(pinakion.balanceOf(address(core)), 1000, "Wrong token balance of the core");
         assertEq(sortitionModule.totalStaked(), 1000, "Wrong totalStaked before withdrawal");
 
+        vm.prank(address(core));
+        pinakion.transfer(staker2, 1000); // Manually send the balance to trigger the revert
+
+        vm.expectRevert(KlerosCore.TransferFailed.selector);
+        sortitionModule.withdrawLeftoverPNK(staker1);
+
+        vm.prank(staker2);
+        pinakion.transfer(address(core), 1000); // Transfer the tokens back to execute withdrawal
+
         vm.expectEmit(true, true, true, true);
         emit SortitionModule.LeftoverPNKWithdrawn(staker1, 1000);
         sortitionModule.withdrawLeftoverPNK(staker1);