Weird irreproducible error

[Steve Heller <steve@...>]

When running exactly the same test with the same data over and over, I
keep getting different results, usually with a message that says
"attempt to index field '?' (a nil value)", in different places in my
code. If I run under the ldb debugger and inspect the data that is
supposedly nil, it actually isn't.

I'm using 5.1.2. Has anyone seen this behavior before?

Thanks.

Steve