Does the "url" property ever go out of type?

I need to subscribe to router events: NavigationStart

andNavigationEnd

this._router.events
        .filter(event => event instanceof NavigationStart || event instanceof NavigationEnd)
        .subscribe((event: NavigationStart | NavigationEnd) => {
            if (event instanceof NavigationStart) {
               // event.url, typescript does not flag any error
            }
            else if (event instanceof NavigationEnd) {
               // typescript flags, that property "url" does not exist on type "never".
               // if I make this block as the only block,
               // i.e. remove the previous "if" block and put this under "if"
               // then it works fine
            }
            // event.url, works fine, even here
        });

      

        
        
        
      

    

Why doesn't typescript recognize it event

as a type NavigationStart

or NavigationEnd

? Although when I console the "event" inside the "else if" I get all the properties of the "event".

I saw this ssylku1 (did not work for me) and this problem , people have given different reasons for the closure of this issue design limitations

. Is there a workaround that I want to achieve,other than doing:

.subscribe((event: any) => {})

      

        
        
        
      

    

EDIT: Implementation of @ Saravana's solution