Prefer early returns

It is recommend to throw/return early so we can ensure null-checks and prevent further nesting.

Instead of doing:

function handler(req, res) {
  const session = await getSession({ req });
  if (session) {
    const user = getUserFromSession(session)
    
    if (user) {
      return res.status(200).json({ user });
    }
    return res.status(404).json({ message: "No user found" });
  }

  res.status(401).json({ message: "Not authenticated" });
}

Do:

function handler(req, res) {
  const session = await getSession({ req });
  if (!session) return res.status(401).json({ message: "Not authenticated" });
  
  const user = getUserFromSession(session)
    
  if (!user) return res.status(404).json({ message: "No user found" });

  return res.status(200).json({ user });
}

It is recommend to throw/return early so we can ensure null-checks and prevent further nesting.