Sending a translation-type message containing "%0" causes the game to freeze

This issue has been around since ~0.15, but until recently I had no way to reproduce this in vanilla.

From a server, sending a TextPacket with the Translation type, containing the characters "%0" will cause any clients receiving it to freeze and ultimately crash.

This is now reproducible in vanilla by typing, for example, /me %0 or /say %0.

Expected result

• Client should simply output "%0" or ignore the message

Actual result

• Client freezes

Tested on MCPE 1.1.0.8 and MCW10 1.0.7.0 in both singleplayer and on servers.