utils: urldecode: Fix bounds check

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utils.cpp

@@ -63,11 +63,12 @@ std::string utils::html_xss(std::string_view str)
 std::string utils::urldecode(std::string_view str)
 {
 	std::string result;
-	int size = str.length();
-	for(int i = 0; i < size; i++)
+	size_t size = str.length();
+	for(size_t i = 0; i < size; i++)
 	{
 		char c = str[i];
-		if(c == '%' && (size - i > 1))
+
+		if(c == '%' && i + 2 < size)
 		{
 			char h[3];
 			h[0] = str[i + 1];