Developing a good design website is an important skill, but let’s not forget that our code will be deployed in production environment and thousands will consume it. That may lead to a nightmare: you get a stack trace of a bug, but wait, it is minified and packed, you have no idea what this bug is or how to reproduce it. In this talk we will take Michael rich experience in production environment and go from case to case to learn from other people’s mistakes. This talk was presented at React Native EU 2017, September 6-7, Wroclaw, Poland.