feat: substitute calcSlashedAmount for scaleForBurning

Author: nadir-akhtar

src/contracts/core/DelegationManager.sol

@@ -3,6 +3,7 @@ pragma solidity ^0.8.27;
 
 import "@openzeppelin-upgrades/contracts/proxy/utils/Initializable.sol";
 import "@openzeppelin-upgrades/contracts/security/ReentrancyGuardUpgradeable.sol";
+import "forge-std/console.sol";
 
 import "../mixins/SignatureUtilsMixin.sol";
 import "../mixins/PermissionControllerMixin.sol";
@@ -793,8 +794,8 @@ contract DelegationManager is
         // less than or equal to MIN_WITHDRAWAL_DELAY_BLOCKS ago. These shares are still slashable.
         uint256 scaledSharesAdded = curQueuedScaledShares - prevQueuedScaledShares;
 
-        return SlashingLib.scaleForBurning({
-            scaledShares: scaledSharesAdded,
+        return SlashingLib.calcSlashedAmount({
+            operatorShares: scaledSharesAdded.mulWad(prevMaxMagnitude),
             prevMaxMagnitude: prevMaxMagnitude,
             newMaxMagnitude: newMaxMagnitude
         });

src/contracts/libraries/SlashingLib.sol

@@ -178,6 +178,10 @@ library SlashingLib {
         uint256 prevMaxMagnitude,
         uint256 newMaxMagnitude
     ) internal pure returns (uint256) {
+        if (prevMaxMagnitude == 0) {
+            // TODO: consider throwing an error instead
+            return 0;
+        }
         // round up mulDiv so we don't overslash
         return operatorShares - operatorShares.mulDiv(newMaxMagnitude, prevMaxMagnitude, Math.Rounding.Up);
     }