Having two stacks that exceed their max stack size and then combing them to have a stack over 99 on your cursor can crash your game if you drop the stack outside of your inventory menu when in creative mode.

Steps to reproduce:

1. Spawn two armor stands holding 99 stacks of an item:

   /summon minecraft:armor_stand ~ ~ ~ {HandItems:[{id:"diamond",count:99}]}

2. Put the two stacks in separate hotbar slots by right clicking the armor stands
3. Combine them in your inventory by clicking the two stacks, creating a stack over 99 on your cursor
4. Drop this stack outside of your inventory window while in creative mode.

Observed result:
The game kicks you from your world.

Expected result:
The game does not kick you from your world.