I created a magical stick using MCedit, gave it Knockback Resist, Speed, Attack Damage and Max Health attributes. Then I modified it's item string, giving it some colored and bold item strings.

After returning to normal minecraft, opening the chest where the stick was caused the game to crash. I tried it about three more times, but the game still crashed. Destroying the chest where the stick was made the game crash once it got into my hotbar.

The crash is probably due to item strings and attributes on a same item causes the game to crash.