What component of google-cloud-cpp is this related to?

Storage.

Describe the bug

When using an storage::ObjectWriteStream some operations can result in a crash, for example:

void F(gcs::Client c) {
  auto stream = c.WriteObject(...);

  std::move(stream).Suspend();
  stream.last_status(); // <-- crash
}

void G(gcs::Client c) {
  auto stream = c.WriteObject(...);

  auto os = std::move(stream); 
  stream.last_status(); // <-- crash
}

Expected behavior

The class should not crash, maybe return the last before the move-from, or maybe return Status(StatusCode::kInvalid, ...).