Hextech crafting crashes my client

Restarting the client should solve this, if it doesn't.

Repair the game by clicking the question mark icon to the top right of the patcher. Select "Repair" and let the patcher scan and repair corrupt game files. When the process is completed, you'll see the orange "Launch" button.

http://eune.leagueoflegends.com/sites/default/files/styles/scale_xlarge/public/upload/template_lcu_changelog_1280x720.jpg?itok=uV6zjzTq