How to fix passport.js passport.initialize() middleware not in use with Node.js?

To fix passport.js passport.initialize() middleware not in use with Node.js, we call app.use with the middleware returned by initialize.

For instance, we write

app.use(
  cookieSession({
    maxAge: 30 * 24 * 60 * 60 * 1000,
    keys: [keys.cookieKey],
  })
);
app.use(passport.initialize());
app.use(passport.session());

to call app.use with the function returned by initialize to add Passport to our Express app.

We call cookieSession to return a middleware to let us use cookie sessions.