In a software development company, the development team is working on a critical project that involves the creation of a web application to handle sensitive user data. The company emphasizes the importance of secure coding practices and robust authentication and authorization mechanisms. Please answer the following questions:

$($i$)$ Identify and explain any THREE $(3)$ common vulnerabilities that can be introduced during software development if secure coding practices are not followed.

$($ii$)$ Based on your answer $3($a$)($i$)$; propose secure coding measures and best practices to mitigate potential vulnerabilities you identified, covering areas such as input validation, error handling, andsecure session management.