`IndexError` in `has_multiple_children`

[The-Compiler]

Dodo just crashed for me after sending a mail. Not sure which parts of the log are related as there are no timestamps:

Processed 7 total files in almost no time.
Added 1 new message to the database.
Folder Sent [acc: uberspace]:
 Syncing Sent: IMAP -> Maildir
 Copy message UID -2 (1/2) local:Sent -> remote:Sent
 Copy message UID -1 (2/2) local:Sent -> remote:Sent
Folder sent [acc: uberspace]:
 Syncing sent: IMAP -> Maildir
[...]
Folder spam [acc: uberspace]:
 Syncing spam: IMAP -> Maildir
Error opening /home/florian/mail/Sent/new/1733838287.M811583P195996Q6.fawkes:2,S: No such file or directory

followed by:

Traceback (most recent call last):
  File "/home/florian/proj/dodo/dodo/panel.py", line 84, in focusInEvent
    self.refresh()
  File "/home/florian/proj/dodo/dodo/thread.py", line 623, in refresh
    self.model.refresh()
  File "/home/florian/proj/dodo/dodo/thread.py", line 316, in refresh
    roots = self.compute_roots(data)
            ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/florian/proj/dodo/dodo/thread.py", line 290, in compute_roots
    return make_thread_trees(raw_data)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/florian/proj/dodo/dodo/thread.py", line 243, in make_thread_trees
    if has_multiple_children(raw_thread_data):
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/florian/proj/dodo/dodo/thread.py", line 241, in has_multiple_children
    forest = forest[0][1]
             ~~~~~~~~~^^^
IndexError: list index out of range