One thing that backend slowly taught me... When I started learning backend, my focus was always on the happy path. I used to think, user sends the correct data, backend processes it, response goes back. If that flow was working, I felt like "okay, it's done." But with time I realized that's only one side of the story. Now, whenever I build something, I spend more time thinking about the unhappy path. What if the data is wrong? What if the user doesn't send a required field? What...