I can't manage to get your error, but, if I save the function (you forgot to do so ?) with Ctrl+B, and reevaluate the last sample, I get an infinite loop in exp2vector() on line 6. In a way, I don't understand anything about the numerical assignations inside exp2vector(), but I think you tried to convert a0 * X0^n + a1 * X1^n-1 + a2 * X2^n-2 + ... + an to [a0, a1, ..., an] didn't you ? Because you can do this with the built-in function polyCoeffs() (available at least in OS 3.0, don't know if it exists before) and returns {a0, a1, ..., an}.
I Hope this helped you.
