mozilla/browserid — comment on commit ef441617cbf020b21d91b989ca1d71c2f4590fa9
File: lib/db/mysql_wrapper.js line 73
By lloyd:

we have one counter that reports the total time that queries take. We could add another, one that we should *never* see - but should it be "slow queries" or should it be "failed queries"?

If we intercept the callback to client code and detect non-null err values there, it will catch many more cases where queries are failing, I lean toward that.