Yes, as noted by jcl in that thread, it will be corrected in the next version, meanwhile you can correct yourself the code. This is the correct one:
// Simple ATR based on SMA
var ATRS(int Period)
{
Period = max(1,Period);
var vATRS = 0;
for(g_count = 0; g_count < Period; g_count++)
vATRS += priceHigh(g_count)-priceLow(g_count);
return vATRS/Period;
}