correct occasional type errors in guideErrors keyword

We are occasionally getting guideErrors keys with None in float fields. Those need to be nan. For example:

guideErrors=463172,-19.662052040938764,-35.52927471548557,nan,None,None,nan,nan

Seems to always be on the alt and az fields.

As an aside, I was very puzzled not to find any ag logs between 2023-07 and 2024-03, even the semi-internal tron traffic logs, and the ag logs on ag-ics.