First of all I want to express that I feel this question belongs in here and not in workplace because it's an interpersonal thing more than a work thing and I'd like a more general answer.
So I was talking (via slack) with my project manager and she asked me to take a look at a document to double check it, I found a mistake and made her know and she said
that was dumb of me. I didn't know what to say afterwards so I waited for her next message to continue the conversation but it took a few minutes while she fixed the mistake.
What is something that you can answer when someone calls themselves dumb without being rude or inappropriate? I feel like laughing it of and or agreeing would be very rude.