Blitz hook didn't pull through

I've seen a Blitz hook catch someone and pull them towards a friendly Shaco trap and the fear from the trap stopped the pull. I've only seen this when the champion Blitz is pulling is far away and already near a Shaco trap but hasn't activated it yet. The trap has to be in the line of fire of the Blitz hook and activated by the champion being pulled mid-pull. I'm not sure if this is meant to happen and I'm not sure how often it can be reproduced but I've seen it happen a couple of times and it's unfortunate for the Blitz player.