Wrong result in Soulmate::totalSouls function, could cause a participant to enter again and be his own soulmate

• Description:

• If an USER call the Soulmate::totalSouls to see the numbers of participants before apply on Soulmate::mintSoulmateToken, and apply being the soulmate[0], when the USER checks Soulmate::totalSouls again, the value will be the same. So the user could try Soulmate::mintSoulmateToken again and he will became his own soulmate.

• Impact:

• This problem could cause many people to became their own soulmates.

• Proof of Code:

  1. USER call the Soulmate::totalSouls

  2. Receive a number

  3. Call Soulmate::mintSoulmateToken

  4. If the USER is the soulmate[0], he will call Soulmate::totalSouls and receive the same number

  5. User could call Soulmate::mintSoulmateToken again, trying to enter on a second time.

  6. Now the Soulmate::totalSouls will update. However, the user will be his own soulmate.

  Add the code bellow to `Soulmate.t.sol` file

  function test_MintNewTokenTotalSouls() public {

  ​

  vm.prank(soulmate1);

  soulmateContract.mintSoulmateToken();

  ​

  vm.prank(soulmate2);

  soulmateContract.mintSoulmateToken();

  ​

  assertTrue(totalSouls == 2);

  ​

  vm.prank(soulmate3);

  soulmateContract.mintSoulmateToken();

  ​

  uint256 totalSouls = soulmateContract.totalSouls();

  ​

  assertTrue(totalSouls == 2);

  }

• Recommendation:

• We can add a counter in Soulmate::mintSoulmateToken to count soulmates

  See the suggestion below

  + uint256 private s_soulsCounter;

  ​

  function mintSoulmateToken() public returns (uint256) {

  ​

  address soulmate = soulmateOf[msg.sender];

  if (soulmate != address(0))

  revert Soulmate__alreadyHaveASoulmate(soulmate);

  + s_soulsCounter++;

  address soulmate1 = idToOwners[nextID][0];

  address soulmate2 = idToOwners[nextID][1];

  if (soulmate1 == address(0)) {

  idToOwners[nextID][0] = msg.sender;

  ownerToId[msg.sender] = nextID;

  emit SoulmateIsWaiting(msg.sender);

  } else if (soulmate2 == address(0)) {

  idToOwners[nextID][1] = msg.sender;

  ​

  ownerToId[msg.sender] = nextID;

  soulmateOf[msg.sender] = soulmate1;

  soulmateOf[soulmate1] = msg.sender;

  idToCreationTimestamp[nextID] = block.timestamp;

  ​

  emit SoulmateAreReunited(soulmate1, soulmate2, nextID);

  _mint(msg.sender, nextID++);

  }

  ​

  return ownerToId[msg.sender];

  }

  ​

  function totalSouls() external view returns (uint256) {

  - return nextID * 2;

  + return s_soulsCounter;

  }