When I joined the company I am with right now, I wanted to jump into the codebase and start working on something, the way I get myself familiar with a codebase

When I joined the company I am with right now, I wanted to jump into the codebase and start working on something, the way I get myself familiar with a codebase is reading the code, but it has to have a goal. I have to understand a piece of the code to use it (API with bad documentation), or because I need to fix a bug or add a feature. I started working on the bugs by choice, it was an easier way to familiarise myself with the source code and gave me some problems that the other developers hadn't been able to fix, or hadn't gotten to yet.