refactor: Refactored middlewares to use RequestError

Refactored middlewares to use RequestError rather than using
`try {...}catch (err){...}`. With this change it's possible to manage
all error details within one place.

Added:
- Added Sentry.captureException to Error Handler

backend/src/helpers/membership.ts

@@ -21,6 +21,7 @@ const validateMembership = async ({
 }) => {
 	
 	let membership;
+	//TODO: Refactor code to take advantage of using RequestError. It's possible to create new types of errors for more detailed errors
 	try {
 		membership = await Membership.findOne({
 			user: userId,