Professional engineering practice admits the possiblity of errors and ommissions. Insurance is the technique used to address it. In ordinary practice this is something that is purchased from agents with an associated cost. In the case of Hubble, it was purchased for the cost of making the telescope serviceable. Infallability is not an engineering practice. "Don't screw up" is not an engineering heuristic.

Fair point, but 'messing it up' to such a high degree of accuracy that it could be corrected for via COSTAR does show soundness of engineering.

Ie, mistakes will inevitably happen. But having the process refined enough to compensate, improvise, and enhance on original plans and imperfections does show good design.

You're right, and it's a funny kind of right.

It's an astounding thing when you're creating a mirror closest to perfection that had ever been made, and missing by 2.2 micrometres ruins it. And given that it was the 1980s and you're dealing with nano scale engineering, it was just that much more incredible.

I should have made my point slightly more clear. I think that the OP's post is actually a non-sequitur. Both statements are generally true, but neither necessarily follows from the other.