I'm asking for approaches to include interesting, but not perfectly fitting results in a dissertation or a paper.
During my PhD project I have made an accidental discovery, which is what I believe you call serendipity. The finding is related to the overall topic of my dissertation and certainly interesting, but it interrupts the "leitmotif" of my argumentation, as this discovery is really just the result of a stupid mistake. So my question here is: How do you eloquently include stupid mistakes (aka accidental findings) in a dissertation or a paper without sounding stupid or breaking the flow of arguments apart? Is there even a generalizing answer to this question?