All Astronauts

Actually looked. It's plupload, the underlying js library that powers the uploader for attachments. A nothing burger; probably just initializing.
EDIT: Here's the bit in the code if you are curious:
 

So this is good to go? Just making sure this stuff will write out on CIC installs and not get ignored.
EDIT: Never mind. Just went ahead and confirmed it myself. Works great. Thanks.

There is probably a third-party app that has a hook on \IPS\Dispatcher directly (and not on \IPS\Dispatcher\Front or Admin instead). This is crashing new code IPS has in the init.php method in this latest version. You are a bit stuck until you figure out which app/plugin it is though. 
You'll need to look at core_hooks table, and then look at the 'class' column. You're looking for \IPS\Dispatcher there and NOTHING ELSE. Not \IPS\Dispatcher\Front; not \IPS\Dispatcher\Admin. If you see an entry there that's your app; if it is a plugin id, off to core_plugins you go to find the matching ID number and that's your plugin.
You'll need to set the RECOVERY_MODE constant (true) to stop all the hooks from loading to get access to everything again. You'll need to disable what you found before taking recovery mode off.... but with recovery mode on you don't actually get access to the ACP so you are in a bit of a loop here. You'll probably need access to the DB via phpadmin or something anyways to find what you need anyways (since recovery mode means no ACP etc. etc...) so once you've found your guy you can just set the application off there in that table, same for plugin.
On the off-chance things are still wonky, you may need to hack out the new IPS code in init.php and everything will work again but you'll need to still deal with whatever is crashing out here. If it gets to that point see my post in the dev area (if you have access there) or shoot me a PM.