Despite being "indie" and "small", Terraria is enormously complex as a piece of software. No two people play it the same way, and every world is different. Combine that with thousands of different mobile devices (and the OS implementation on each is slightly different), and you have the potential for a lot of bugs and glitches.
There is no doubt that the QA process failed here - there should not have been this many bugs and crashes. It seems clear that the QA people had little to no experience playing Terraria as people tend to play it; going forward we hope to have a team of 'Terraria experts' to do the gameplay testing - people who will recognize when a weapon isn't dealing the proper damage or looks wrong. We could not get that team in place in time for this update, unfortunately.