What are strategies to prevent upstream dependency conflicts in the first place?

Preventative measures include using lock files (`package-lock.json` or `npm-shrinkwrap.json`) and committing them to version control. This ensures consistent installations across environments. Regularly updating dependencies to their latest compatible versions using tools like `npm-check-updates` can also help. Furthermore, being mindful of the dependencies you add to your project and their own dependencies can mitigate future issues.