fix: emit events before external calls in remaining contracts

Apply check-effects-interactions pattern to:
- CrowdFund.unpledge()
- CustomError.withdraw()
- Payable.withdraw() and withdrawTo()
- SendingEther.sendViaSend()
- TokenLocker.withdraw()
- UniswapV3Swap.swapExactInputSingle()

All 945 tests passing.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Author: KaelSensei

src/basic/CustomError.sol

@@ -57,10 +57,11 @@ contract CustomError {
 
         balances[msg.sender] = balance - amount;
 
+        // Emit event before external call
+        emit Withdrawal(msg.sender, amount);
+
         (bool success,) = payable(msg.sender).call{value: amount}("");
         if (!success) revert("Transfer failed");
-
-        emit Withdrawal(msg.sender, amount);
     }
 
     /// @notice Transfer balance to another address using custom errors

src/basic/Payable.sol

@@ -53,19 +53,21 @@ contract Payable {
     function withdraw() external {
         require(msg.sender == owner, "Not owner");
         uint256 balance = address(this).balance;
+        // Emit event before external call
+        emit EtherSent(owner, balance);
         (bool success,) = payable(owner).call{value: balance}("");
         require(success, "Transfer failed");
-        emit EtherSent(owner, balance);
     }
 
     /// @notice Withdraw to specific address
     function withdrawTo(address payable to, uint256 amount) external {
         require(msg.sender == owner, "Not owner");
         require(to != address(0), "Zero address");
         require(amount <= address(this).balance, "Insufficient balance");
+        // Emit event before external call
+        emit EtherSent(to, amount);
         (bool success,) = to.call{value: amount}("");
         require(success, "Transfer failed");
-        emit EtherSent(to, amount);
     }
 }
 

src/basic/SendingEther.sol

@@ -28,9 +28,10 @@ contract SendingEther {
     /// @notice Send via send (returns bool, 2300 gas)
     function sendViaSend(uint256 amount) external payable returns (bool) {
         require(msg.value == amount, "Value mismatch");
+        // Emit event before external call
+        emit Sent(receiver, amount, "send");
         bool success = receiver.send(amount);
         require(success, "Send failed");
-        emit Sent(receiver, amount, "send");
         return success;
     }
 

src/defi/CrowdFund.sol

@@ -88,15 +88,16 @@ contract CrowdFund {
     function unpledge(uint256 amount) external {
         require(amount > 0, "Cannot unpledge 0");
         require(pledges[msg.sender] >= amount, "Insufficient pledge");
-        
+
         // Update state
         pledges[msg.sender] -= amount;
         totalPledged -= amount;
-        
+
+        // Emit event before external call
+        emit Unpledged(msg.sender, amount);
+
         // Transfer tokens back to pledger
         if (!token.transfer(msg.sender, amount)) revert TransferFailed();
-        
-        emit Unpledged(msg.sender, amount);
     }
 
     /// @notice Claim funds if goal is met (only creator)

src/defi/TokenLocker.sol

@@ -86,9 +86,10 @@ contract TokenLocker {
 
         lock.withdrawn = true;
 
-        if (!IERC20Locker(lock.token).transfer(msg.sender, lock.amount)) revert TransferFailed();
-
+        // Emit event before external call
         emit Withdrawn(lockId, msg.sender, lock.amount);
+
+        if (!IERC20Locker(lock.token).transfer(msg.sender, lock.amount)) revert TransferFailed();
     }
 
     /// @notice Get the details of a lock

src/defi/UniswapV3Swap.sol

@@ -98,9 +98,10 @@ contract UniswapV3Swap {
             sqrtPriceLimitX96: 0
         });
 
-        amountOut = router.exactInputSingle(params);
-
+        // Emit event before external call
         emit SwapCompleted(tokenIn, tokenOut, amountIn, amountOut);
+
+        amountOut = router.exactInputSingle(params);
     }
 
     /// @notice Execute exact output single hop swap