Sort array of objects alphabetically by property with special characters

Question

I am trying to sort alphabetically array of objects based on their usernames. Basically array of users is something like this

users = [
{ 
  firstName: 'Ana'
  lastName: 'Smith'
  username: 'Ana'
  id: 1
  email: 'ana@ana.com'
},
{ 
  firstName: 'Ana'
  lastName: 'AnaWithSpecialA'
  username: 'Äna'
  id:2
  email: 'ana2@ana.com'
},
{ 
  firstName: 'Bla'
  lastName: 'Blabla'
  username: 'Bla'
  id:3
  email:'bla@bla.com'
}
]

I use this function for sorting:

users.sort((a, b) => {
  if(a.username < b.username) return -1;
  if(a.username > b.username) return 1;
  return 0
});

But users with usernames that start with Ä, Ö, Ü always end up last. This is German alphabet letters btw. How can I push them so that Ä can be behind A and Ö behind O etc, or whatever is the correct way of sorting?