Killed repeatedly while defenseless due to Building Terrain in nether.

Having entered the nether, in hard difficulty, I have a skeleton camping on my nether portal. When I attempt to jump to the nether, I am killed by the skeleton while the "Building Terrain" load screen is showing. I can hear the hits, but cannot do anything because of the load screen. Please ensure that the player does not become vulnerable to attack until they can defend themselves. Thank you.