I'll walk you through it.

I did not claim (as you imply) that the fact of there being a programming error was what implied that there is "an inconsistency in its reasoning." In the two paragraphs immediately before the one you quote (and, indeed, in that whole section), I explain that the system KNOWS that it is following these two imperatives:

1) Conclusions produced by my reasoning engine are always correct. [This is the Doctrine of Logical Infallibility]

2) I know that AGI reasoning engines in general, and mine in particular, sometimes come to incorrect conclusions that are the result of a failure in their design.

Or, paraphrasing this in the simplest possible way:

1) My reasoning engine is infallible.

2) My reasoning engine is fallible.

That, right there, is a flat-out contradiction between two of its core "beliefs". It is not, as you state, that the existence of a programming error is evidence of inconsistency, it is the above pair of beliefs (engendered by the programming error) that constitute the inconsistency.

Does that help?