You're trying to use a component which isn't installed. Might be worth checking which components you're using in your json (_component attribute) vs which are installed.

Or one of your components is missing the _component attribute in the json?

I'll get a good error message written, apologies for the random error.

Seeing as you're in the debugger already, it might be worth looking at which json._component is failing. Might give you a hint

Ollie.

It's most likely that you're trying to use a component that isn't installed - or that something is wrong in the .json

It should be handling this more gracefully than it is though, we'll get that fixed.

I've literally just merged a fix for this, so you'll get a more useful error message if you encounter this issue after the next release :)