Back in those days when we couldn’t patch games post-release, our team felt it was much too dangerous to change anything for the release for fear of code layout changing exposing some bug which had previously been harmless and undetected by QA, and so we would typically leave all of our debugging tools and runtime checks enabled in the final release builds of the game. It was just safer that way.

But with that said, we didn’t generally crash the game due to a missing texture, even during development, as that’s a super common problem which would have impacted development too much; instead, we just drew anything which used a missing texture in max-saturation pink and green instead, alternating between the two colors once per second, to make sure it’d be super visible to anyone looking at the game during development.

We did usually change that behaviour to instead render missing tetxures in alternating black/near-black instead of pink/green for our final releases, as that was deemed a relatively safe change.