Fix or remove "Estimate of factor X is numerically zero!" warnings

[pcarbo]

@willwerscheid Discussed on Slack and posted here as a reminder to us.

I'm getting these warnings sometimes:

Difference between iterations is within 1.0e+00...
--Estimate of factor 1 is numerically zero!
--Estimate of factor 2 is numerically zero!
Difference between iterations is within 1.0e-01...
Difference between iterations is within 1.0e-02...
Difference between iterations is within 1.0e-03...

I can provide a reproducible example if you would like.

Matthew said: "Maybe the message needs changing to be less dramatic."

Jason said: "It does not remove the factor. If you saw that message it has been set to zero."

We discussed that perhaps the easiest solution is to remove this message.