I haven't made any mistakes yet as in I'm working on a completely new project - I haven't interacted with any of the pre-existing code at all, so I haven't had any chances to screw something up. When I'm done, I'll merge my project into their codebase and that'll be it.

Hm, I ask because it's a good way to see what type of learning environment it will be. Maybe pay attention to how the people around you are treated after a mistake is made.

I did make a mistake on a personal note and my boss was very relaxed and fair about that. In general, people don't seem to have any problems helping each other out at all. Now that I think about it, its a great work environment, and the CEO has a very good track record too. Also judging from our funding and customers, we're going to do well! Guess that answers my questions then :p.