Re: Weird error: two similar strings are not equal

[Dirk Laurie <dirk.laurie@...>]

>>>  -- return value #2 mismatch: actual `""', expected `""'
>>>  -- return value #4 mismatch: actual `"luatexts"', expected `"luatexts"'
...

> I think there's nothing obviously wrong with luatexts, because this
> error occurs not every time.

Do you mean you run exactly the same program with exactly the same
data more than once and the error is not reproducible?

...
> I think there's nothing obviously wrong with luatexts, because this
> error occurs not every time. And I also believe ensure_returns() (part
> of lua-nucleo library) works correctly.
...
> Can there be other possibilities?
>

You seem to be running LuaJIT.  Do you get the same error:

  - if you use a different version of LuaJIT?
  - under Lua 5.1.5?
  - with the same software but on a different computer?