Fix typographical errors (#5171)

Signed-off-by: Hadrien Croubois <hadrien.croubois@gmail.com>

contracts/utils/math/SignedMath.sol

@@ -58,10 +58,10 @@ library SignedMath {
             // Since `n` is a signed integer, the generated bytecode will use the SAR opcode to perform the right shift,
             // taking advantage of the most significant (or "sign" bit) in two's complement representation.
             // This opcode adds new most significant bits set to the value of the previous most significant bit. As a result,
-            // the mask will either be `bytes(0)` (if n is positive) or `~bytes32(0)` (if n is negative).
+            // the mask will either be `bytes32(0)` (if n is positive) or `~bytes32(0)` (if n is negative).
             int256 mask = n >> 255;
 
-            // A `bytes(0)` mask leaves the input unchanged, while a `~bytes32(0)` mask complements it.
+            // A `bytes32(0)` mask leaves the input unchanged, while a `~bytes32(0)` mask complements it.
             return uint256((n + mask) ^ mask);
         }
     }