Compare Rust's https://doc.rust-lang.org/std/str/fn.from_utf8.html
If you've got a buffer full of bytes, which you hope are UTF8 text but maybe aren't, call std::str::from_utf8 and you either get back a string slice with your text in it, or you get a std::str::Utf8Error structure which explains what the problem was in an actionable format. You can write code to process this Utf8Error and your bytes - maybe you're reading blocks of data and it's all valid UTF8 but the last character is continued in the next block for example, you can discern that from Utf8Error and just turn the valid part into UTF8 and keep the rest until the next block is available.
Indeed, I recently updated some code to return a relevant value in the error case: https://github.com/wal-g/wal-g/pull/1143/files#diff-d896e5d5... where true means the error is rooted in a corrupted page, & false means that the error isn't due to a corrupted page. It does feel a little dirty & a comment is probably necessary to make this case clear
Still, Result can work here. For example, Rust's binary_search https://doc.rust-lang.org/std/vec/struct.Vec.html#method.bin... which returns Ok(idx) when that's the location of the element, or Err(idx) when that's the location the element would be if it were there (this can be a bit annoying when you just want to insert, since you end up writing `let idx = match result { Ok(idx) => idx, Err(idx) => idx }`)