Instead, give a %no-mail response message. It's not entirely unexpected
to encounter ships that don't have a hosting account email address
associated with them, so it shouldn't be a reason to crash.
The crash is particularly problematic because as of the previous
commits, we now actually show the trace of thread crashes.
The "save summary" thread still had hark flagged as one of its dependencies,
but doesn't actually use that for anything anymore.
Here we simply remove the import.
