Unable to open the inventory on riding a horse.

On riding a horse, I press my inventory key and then I crashed.
Evidence : https://youtu.be/-obRELqbkYg
Console log :

[18:40:19] [Server thread/INFO]: unixfox lost connection: TextComponent{text='Disconnected', siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null, insertion=null}}

Crash screenshot : http://puu.sh/jhBfY/49322d3a5c.png