That worst case shouldn't happen. When you do something like this:

  let data = serialize(&doc)
      .or_raise(|| StorageError::permanent("serialization failed"))?;

you're burying the error thrown by `serialize(&doc)` in such a way that you have to dig for it dynamically to recover it.

The closure in `or_raise` should take the error from `serialize(&doc)` as an argument and save the actionable details. It makes sense to have an "outermost error" when you're talking about a context trace that provides information to humans, but an error which a machine responds to should be flat & statically matchable.

Something like this:

  let data = serialize(&doc)
      .or_raise(|e| Exn::with_message(
          "serialization failed",
          StorageError::fromInner(e)))?;

where `StorageError::fromInner` decides whether the error should be permanent or not based on the contents of `e`, and saves any details that would be relevant for automatically recovering from the error.