This has happened to me twice in the last 24 hours... I have submitted a diff with `arc diff` and everything seemed fine from the client side (no errors or warnings). However, when I go to view the diff in #differential I get an exception:
```
This revision has no diffs. Something has gone quite wrong.
```
I poked around in the error logs from the server yesterday and couldn't see anything related, but I might poke around again.