From what I can tell from the lua source, it allows a stack of 200 C-calls
unless compiled with a different limit.
The only catch is that any custom C-call must handle yields by itself (any
assumption on lua's part would limit what can be implemented).

With commit 94141d3d63370ad068c92f1c135ccf40900294bf this message won't appear
again, but a similar one is guaranteed to appear again until yields are handled
by all lua C-functions that execute other lua code.

My patch only results in yields being treated as returns.
I'm not sure if it's a proper fix because I can't grasp the intended use of lua,
can't even understand why there are two lua states.