IS THIS A BUG

I use evelynn playing jg in a rank game, everything was normal and good ,but after i got double buffs, my game just got crushed, I can still move , but i can't do anything else. I wanna gank top, then pinged top and walk to there, when i got top, their top laner was just suddenly disappeared. And somehow i died there, i don't even know what i've done, is this a bug? is there any one know this or have seen this before? thanks