Update StdMath.sol

Author: viktorking7

src/StdMath.sol

@@ -29,6 +29,8 @@ library stdMath {
     }
 
     function percentDelta(uint256 a, uint256 b) internal pure returns (uint256) {
+        // Prevent division by zero
+        require(b != 0, "stdMath: percentDelta divisor is zero");
         uint256 absDelta = delta(a, b);
 
         return absDelta * 1e18 / b;
@@ -37,6 +39,8 @@ library stdMath {
     function percentDelta(int256 a, int256 b) internal pure returns (uint256) {
         uint256 absDelta = delta(a, b);
         uint256 absB = abs(b);
+        // Prevent division by zero
+        require(absB != 0, "stdMath: percentDelta divisor is zero");
 
         return absDelta * 1e18 / absB;
     }