What is killing me?

I was travelling a corner of Novigrad seeking a new location on the map, where I reached a weird tree, and any time I got close to it I simply dropped dead. From full health of 6000+ vitality to 0 instantly. No fall. No monsters. No fight. Just walking.

Here is a video: https://www.facebook.com/yahavbr/videos/vb.670059072/10154340184989073

Screenshot from the video:

Here is picture of the location on the map:

And in the world's map:

Is this a bug, if so is there a way to bypass it? I tried about 5 times from different locations before giving up, as each time means long minutes of loading.

You can't get there yet. I wasn't aware there was a death wall, but you'll visit that location later in the game.