 called
from the callback &mdash; no checks for the proper number of arguments
are made. The return value of the Lua function will be converted to the
result type and an error will be thrown for invalid conversions.
</p>
<p>
It's allowed to throw errors across a callback invocation, but it's not
advisable in general. Do this only if you know the C&nbsp;function, that
called the callback, copes with the forced stack unwinding and doesn't
leak resources.
</p>
<p>
One thing that's not allowed, is to let an FFI