I think it depends on the amount and nature of those mistakes. In general, I think we as writers should make reading as easy as we can for our readers - we want them to focus on things like the plot and characters, and not technical stuff like spelling or grammar. I personally find that when I read something that has a lot of mistakes, I end up focusing on them more than the actual story.
I think it's always best to proofread your work, and, if you can, get someone else to edit/proofread/beta read your chapters. It can really help you detect any mistakes you might have missed.
A small mistake here and there can still happen though, which I think is also important to note, and it's not the end of the world. I know it did to me, despite my best efforts, and when I noticed it I simply edited the chapter. As a reader too, when I encountered good novels that had small mistakes here and there they didn't stop me from reading and enjoying them.
TL;DR: try giving your readers a clean, well-edited story, but don't forget to be kind to yourself at the same time.