Fix the audit report issue

contracts/FeralfileArtworkV4.sol

@@ -130,6 +130,12 @@ contract FeralfileExhibitionV4 is
 
         // initialize max supply map
         for (uint256 i = 0; i < seriesIds_.length; i++) {
+            // Check duplicate with others
+            for (uint256 j = i + 1; j < seriesIds_.length; j++) {
+                if (seriesIds_[i] == seriesIds_[j]) {
+                    revert("FeralfileExhibitionV4: duplicate seriesId");
+                }
+            }
             require(
                 seriesMaxSupplies_[i] > 0,
                 "FeralfileExhibitionV4: zero max supply"
@@ -440,6 +446,11 @@ contract FeralfileExhibitionV4 is
                 ) {
                     uint256 rev = (itemRevenue *
                         saleData_.revenueShares[i][j].bps) / 10000;
+                    if (
+                        saleData_.revenueShares[i][j].recipient == costReceiver
+                    ) {
+                        continue;
+                    }
                     distributedRevenue += rev;
                     payable(saleData_.revenueShares[i][j].recipient).transfer(
                         rev
@@ -450,10 +461,10 @@ contract FeralfileExhibitionV4 is
             emit BuyArtwork(saleData_.destination, saleData_.tokenIds[i]);
         }
 
-        // Transfer cost and remaining funds
-        uint256 cost = saleData_.price - distributedRevenue;
-        if (cost > 0) {
-            payable(costReceiver).transfer(cost);
+        // Transfer cost, platform revenue and remaining funds
+        uint256 leftOver = saleData_.price - distributedRevenue;
+        if (leftOver > 0) {
+            payable(costReceiver).transfer(leftOver);
         }
     }
 
@@ -596,11 +607,6 @@ contract FeralfileExhibitionV4 is
         );
     }
 
-    /// @notice withdraw all fund
-    function withdrawFunds() external onlyOwner {
-        payable(msg.sender).transfer(address(this).balance);
-    }
-
     /// @notice Event emitted when new Artwork has been minted
     event NewArtwork(
         address indexed owner,

test/feralfile_exhibition_v4.js

@@ -66,6 +66,32 @@ contract("FeralfileExhibitionV4_0", async (accounts) => {
         assert.equal(seriesTotalSupply1, 0);
     });
 
+    it("test duplicate series in constructor", async function () {
+        // Deploy contract with duplicate series defined 
+        let seriesIds = [0, 1, 2, 3, 1];
+        let seriesMaxSupply = [1, 1, 100, 1000, 10000];
+        try {
+            await FeralfileExhibitionV4.new(
+                "Feral File V4 Test",
+                "FFv4",
+                true,
+                true,
+                this.signer,
+                this.vault.address,
+                COST_RECEIVER,
+                CONTRACT_URI,
+                seriesIds,
+                seriesMaxSupply
+            );
+        } catch (error) {
+            assert.ok(
+                error.message.includes(
+                    "FeralfileExhibitionV4: duplicate seriesId"
+                )
+            );
+        }
+    })
+
     it("test mint artwork", async function () {
         const contract = this.contracts[0];