Fixed navigation to not existing slides (#772)
Fixed navigation to not existing slides (#772)

Co-authored-by: OleksandrDanylchenko <22bd633a058d60b0929394ecd18081ab4db3e346@gmail.com>

Fixes #771 
NUKnightLab/TimelineJS3,NUKnightLab/TimelineJS3,NUKnightLab/TimelineJS3