chore: add comment in _burnBadDebt + lint

docs/Aave-v3.3-features.md

@@ -99,6 +99,7 @@ By flipping the masks:
 ```
 
 The access can be simplified:
+
 ```
 function getLtv(DataTypes.ReserveConfigurationMap memory self) internal pure returns (uint256) {
 -    return self.data & ~LTV_MASK;
@@ -108,7 +109,6 @@ function getLtv(DataTypes.ReserveConfigurationMap memory self) internal pure ret
 
 Which slightly reduces gas & code-size. The effect is getting more meaningful for accounts holding multiple collateral & borrow positions.
 
-
 ### 3. Additional getters
 
 When analyzing ecosystem contracts we noticed that a lot of contracts have to pay excess gas due to the lack of fine grained getters on the protocol.

src/contracts/protocol/libraries/logic/LiquidationLogic.sol

@@ -612,6 +612,9 @@ library LiquidationLogic {
       IVariableDebtToken vToken = IVariableDebtToken(currentReserve.variableDebtTokenAddress);
       // Fetch the scaled balance first as it is more gas-efficient
       uint256 userDebt = vToken.scaledBalanceOf(user);
+      // Prior v3.1, there were cases where, after liquidation, the `isBorrowing` flag was left on
+      // even after the user debt was fully repaid, so to avoid this function reverting in the `_burnScaled`
+      // (see ScaledBalanceTokenBase contract), we check for any debt remaining.
       if (userDebt != 0) {
         // Scale up the debt balance
         userDebt = userDebt.rayMul(reserveCache.nextVariableBorrowIndex);