Changed enumeration to use set size instead of inventory size

src/LSSVMPairMissingEnumerable.sol

@@ -88,7 +88,7 @@ abstract contract LSSVMPairMissingEnumerable is LSSVMPair {
        @notice Returns all NFT IDs held by the pool
      */
     function getAllHeldIds() external view override returns (uint256[] memory) {
-        uint256 numNFTs = nft().balanceOf(address(this));
+        uint256 numNFTs = idSet.length();
         uint256[] memory ids = new uint256[](numNFTs);
         for (uint256 i; i < numNFTs; i++) {
             ids[i] = idSet.at(i);