"if" doesn't work in React's componentWillMount()

I have created a component "App", which has a function componentWillMount defined (it should redirect react router when condition is false).

componentWillMount() {
    const isLoggedIn = session.getLogin()
    console.log( 'isLoggedIn is', isLoggedIn )
    if ( !isLoggedIn ) {
        console.log( 'now its false!' )
    } else {
        console.log( 'else' )
    }
    return false
}

But the console outputs the following:

isLoggedIn is false
else

Am I doing something wrong? I was thinking that having isLoggedIn set to false, the console should say "now its false!", but it doesn't.

Just to note - session.getLogin() does return sessionstorage.getItem('sessionLoggedIn')

Thank you for anwsers.