Completely unrelated. If you have production outages resulting from new code you have serious gaps in your certification process, especially so if the new code covers existing process/requirements. You are probably insecurely reliant upon dependencies to fill gaps you haven’t bothered to investigate, which is extremely fragile.
The benefit of code reuse is simplification. If a new problem emerges with requirements that exceed to current simple solution you have three choices:
1. Refactor the current solution, which introduces risk.
2. Roll an alternative for this edge cases and refactor after. This increases expenses but is safer and keeps tech debt low.
3. Roll an alternative for this edge case and never refactor. This is safe in the short term and the cheapest option. It is also the worst and most commonly applied option.