When you open a Book GUI (Use a book and quill), click the text in it to move the curson and then press a keyboard key (For example one of the arrow key) the Minecraft client crashes with a StringIndexOutOfBoundsException

This was tested on Singleplayer and Also a plain vanilla server without any client-crashes and it only happens in survival (and maybe adventure mode, but not tested) mode and not creative mode.

Full client crash report is attached to this.