The bug

Right clicking a dragon egg near y = 0 or y = 255 can result in it being deleted.

How to reproduce

1. Create a Superflat world completely filled with a block

   3;256*minecraft:stone;127;
   

2. Replace one block at y = 255 and place a dragon egg
3. Right click the dragon egg

Code analysis

Based on 1.11.2 decompiled using MCP 9.35 rc1

The method net.minecraft.block.BlockDragonEgg.teleport(World, BlockPos) does not test if the y-coordinate of the randomly chosen position is inside the valid building height range. Since the method World.getBlockState(BlockPos) returns for positions < 0 and >= 256 air the dragon egg tries to place itself there.

Note: It would be great if the dragon egg would not try to teleport outside the worldborder or at least the 30,000,000 blocks area as well.