Spawning in the air

Chunks don't load properly when creating a new world and then I'm stuck in the ground.

What I expected to happen was...:
When I create a new world I should spawn somewhere on safe ground.

What actually happened was...:
(It seems to happen totally randomly, althtough many trees nearby seem to support this) Sometimes when generating a new world, the chunks load too slow and I'm falling into the void. After some seconds the chunks appear and I get stuck in the ground but I get no damage from falling (I am also on a higher position again, as if there was no fall before). I can get myself free by destroying the block. It also happened once when respawning after death but I couldn't recreate that.

Steps to Reproduce:
Create a couple of maps. It usually appears every 4th creation.