Unable to do a proper check before assigning a variable

I have the following code

let sess = session

let vigilances = sess.usuario.empresasVigi || 0;
let idSess = sess.sesionUsuarioSessionStorage.sesionExt || null;
let balance = sess.saldosUsuarioSessionStorage.saldo || 0;

Sess is an object, but sometimes it is empty so some properties will be missing If that happens I want the variable to be assigned the value after ||, so I have written the code above

But so far , im receiving

Cannot read property 'empresasVigi' of undefined


Use optional chaining

let vigilances = sess.usuario?.empresasVigi || 0;
let idSess = sess.sesionUsuarioSessionStorage?.sesionExt || null;
let balance = sess.saldosUsuarioSessionStorage?.saldo || 0;