update burn

contracts/NonfungiblePositionManager.sol

@@ -97,14 +97,17 @@ contract NonfungiblePositionManager is INonfungiblePositionManager, BaseLiquidit
         isAuthorizedForToken(tokenId)
         returns (BalanceDelta delta)
     {
+        // TODO: Burn currently decreases and collects. However its done under different locks.
+        // Replace once we have the execute multicall.
         // remove liquidity
         TokenPosition storage tokenPosition = tokenPositions[tokenId];
         LiquidityRangeId rangeId = tokenPosition.range.toId();
         Position storage position = positions[msg.sender][rangeId];
-        if (0 < position.liquidity) {
+        if (position.liquidity > 0) {
             (delta,) = decreaseLiquidity(tokenId, position.liquidity, hookData, claims);
-            (delta) = collect(tokenId, recipient, hookData, claims);
         }
+
+        collect(tokenId, recipient, hookData, claims);
         require(position.tokensOwed0 == 0 && position.tokensOwed1 == 0, "NOT_EMPTY");
         delete positions[msg.sender][rangeId];
         delete tokenPositions[tokenId];

contracts/base/BaseLiquidityManagement.sol

@@ -268,18 +268,20 @@ contract BaseLiquidityManagement is IBaseLiquidityManagement, SafeCallback {
         internal
         returns (BalanceDelta callerDelta, BalanceDelta thisDelta)
     {
-        // Do not add or decrease liquidity, just trigger fee updates.
-        // TODO: Fails when position is empty
-        (BalanceDelta liquidityDelta, BalanceDelta totalFeesAccrued) = _modifyLiquidity(owner, range, 0, hookData);
-
         Position storage position = positions[owner][range.toId()];
 
-        // Also updates the position's the feeGrowthInsideLast variables in storage.
-        (BalanceDelta callerFeesAccrued) = _updateFeeGrowth(range, position);
+        // Only call modify if there is still liquidty in this position.
+        if (position.liquidity != 0) {
+            // Do not add or decrease liquidity, just trigger fee updates.
+            (BalanceDelta liquidityDelta, BalanceDelta totalFeesAccrued) = _modifyLiquidity(owner, range, 0, hookData);
 
-        // Account for fees accrued to other users on the same range.
-        // TODO: Opt when liquidityDelta == 0
-        (callerDelta, thisDelta) = liquidityDelta.split(callerFeesAccrued, totalFeesAccrued);
+            // Also updates the position's the feeGrowthInsideLast variables in storage.
+            (BalanceDelta callerFeesAccrued) = _updateFeeGrowth(range, position);
+
+            // Account for fees accrued to other users on the same range.
+            // TODO: Opt when liquidityDelta == 0
+            (callerDelta, thisDelta) = liquidityDelta.split(callerFeesAccrued, totalFeesAccrued);
+        }
 
         // Allow the caller to collect the tokens owed.
         // Tokens owed that the caller collects is paid for by this contract.

test/position-managers/FeeCollection.t.sol

@@ -218,6 +218,8 @@ contract FeeCollectionTest is Test, Deployers, GasSnapshot, LiquidityFuzzers {
 
     /// @dev Alice and bob create liquidity on the same range
     ///     when alice decreases liquidity, she should only collect her fees
+    /// TODO Add back fuzz test on liquidityDeltaBob
+    /// TODO Assert state changes for lpm balance, position state, and return values
     function test_decreaseLiquidity_sameRange_exact() public {
         // alice and bob create liquidity on the same range [-120, 120]
         LiquidityRange memory range = LiquidityRange({poolKey: key, tickLower: -120, tickUpper: 120});