Merge pull request #68 from buttonwood-protocol/rem-l1-fix-cancel-withdrawal-checks

fix(rem-l1): adding check in lender-queue to prevent double cancellation

Author: SocksNFlops

src/LenderQueue.sol

@@ -191,6 +191,9 @@ abstract contract LenderQueue is Context, ERC165, AccessControl, ILenderQueue, R
     // Burn the excess shares that correspond to forfeited yield while the request was in the queue
     if (request.shares > 0 && request.amount > 0) {
       IConsol(consol).burnExcessShares(request.shares, request.amount);
+    } else {
+      // It's not possible to reach this point if the request has already been processed, so it must have been cancelled
+      revert RequestAlreadyCancelled(index);
     }
 
     // Transfer the request.amount of Consols back to the request owner's Account

src/interfaces/ILenderQueue/ILenderQueueErrors.sol

@@ -55,4 +55,10 @@ interface ILenderQueueErrors {
    * @param caller The caller of the function
    */
   error CallerIsNotRequestAccount(address requestAccount, address caller);
+
+  /**
+   * @notice The withdrawal request has already been cancelled.
+   * @param index The index of the withdrawal request
+   */
+  error RequestAlreadyCancelled(uint256 index);
 }