fix crash when invalid tab index on iOS
fix crash when invalid tab index on iOS

rhosilver/rhodes-1,UIKit0/rhodes,louisatome/rhodes,UIKit0/rhodes,louisatome/rhodes,rhosilver/rhodes-1,UIKit0/rhodes,UIKit0/rhodes,louisatome/rhodes,louisatome/rhodes,louisatome/rhodes,UIKit0/rhodes,UIKit0/rhodes,louisatome/rhodes,rhosilver/rhodes-1,rhosilver/rhodes-1,UIKit0/rhodes,louisatome/rhodes,rhosilver/rhodes-1,rhosilver/rhodes-1,rhosilver/rhodes-1,UIKit0/rhodes,rhosilver/rhodes-1,rhosilver/rhodes-1,UIKit0/rhodes,louisatome/rhodes,rhosilver/rhodes-1,UIKit0/rhodes,louisatome/rhodes