So I'm a programmer who works in telecom. I'm currently in school as well and I'm also an avid gamer (shocker). I said this to form my question: Take a big game title such as DotA 2 - how do you know when you're ready to work on a system that complicated?
I work on web applications at work, but they aren't all that complicated. From my perspective, the little errors I make in web dev would never fly in a company like Valve when their game reaches 11 million people monthly. This could apply to any large company with products whose code must hold up at all times. After all, big errors in the code could mean a loss of big dollars.
What I'm asking is, how does one get confident enough to know that code I'm writing is robust enough to not have an insane error show up, while working on a huge system like an online game? How does one approach coding in the midst of incredibly complex systems while producing minimal to no errors?