... except possibly for the part about no prior metaphysical meaning.

I think I see the source of the difficulty now. My fault. BobTheBob mentioned the mistake of replicating with errors. I took this to be just one example of a possible mistake by a virus, and thought of several more - inserting into the wrong species of host, for example, or perhaps incorporating an instance of the wrong peptide into the viral shell after replicating the viral genome.

I then sought to define 'mistake' to capture the common fitness-lowering feature of all these possible mistakes. However, I did not make clear what I was doing and my readers naturally thought I was still dealing with a replication error as the only kind of mistake.

Sorry to have caused this confusion.