A stumble may prevent a fall.
Having been a perfectionist, I can certainly recall times where even making a small mistake would give me an uneasy feeling in my stomach. After seeing someone else go through the exact same thing, I was reminded of this idiom. It helped me to reframe small mistakes and be grateful for them.
It's lucky when we catch a small mistake that prevented a big problem down the road. After all, we are human, and humans make mistakes. We should celebrate the stumbles since they prevent falls.