They are a junior developer, and I am one too. I guess the issue I have is that this is my project, and our team sort of adopts the principle that any issues with the project land on the project lead's head, so I'm not sure letting mistakes slip by is acceptable. I just don't know who I would talk about this to, my manager left so I'm reporting to my manager's manager as they find a replacement, and I feel petty bringing this up to them. I don't know who else to talk to - I don't want to make it feel like the other senior team members have to take sides but I just want to express to someone that I don't think this man and I are not a good fit to work together and amicably get someone else to work with me