Synechron MERN Stack Developer interview questions

how do you do the session management for ex if user closes the tabs how do you handle that how does your microservices connect to database? do you write plain queries or how is it how do you define the schema or what are the key factor you will consider? what are the security measure while developing web applications on UI(react) what are the hooks you have used? what kind of error handler you used in your application? how does the error flows from backend or front end? what are the key factors you consider while designing the error middleware?