The offending routine is _log_int (I'm sure you knew that) which requires 2 arguments (the number and the base to which the log is to be taken; I'm sure you knew that, too).

Actually you are wrong... being sure I knew. In fact I didn't. I suppose it would have been easy to know. But I wasn't extremely interested, just stumped into this, and felt like reporting. I was quite confident this may be a real bug of the module, for once (generally a perceived bug), but preferred discussing the issue here. I'll report it to the author as well.