Fix another useless use of loop.
Handle more conditions, fix #57.

Turns out that in cases it's not possible to call format-vector-row on
MySQL result sets, because it's been sending us vector of bytes (blob)
while the expected data (from the table definition) clearly is text.

Handle the error as an input reading error, skipping the line and being
verbose about it in the logs. This patch fails to update the stats about
what's happening because, so might need later changes.