Nate Lust & I discussed the scope of this ticket earlier.
We're agreed that there are a lot of linter errors in obs_subaru, and we should eliminate them. However, this effort we've allocated to this ticket was on the basis of (fully, i.e. more so than now!) cleaning up the errors listed in the ticket description, rather than finding and fixing all possible errors throughout the package. Furthermore, since we expect to be able to eliminate some of the package's code (DM-4740), it wouldn't make sense to spend time on fixes before that ticket is implemented.
Therefore, Nate will fix the three errors listed in this ticket description and file a new ticket, blocked by DM-4740, to eliminate further errors.