Traceback when adding very first bookmark

Steps to reproduce

Connect poezio to new empty account
/bookmarks
M-a
What happens

Traceback (most recent call last):
  File "/usr/lib/python3.7/asyncio/events.py", line 88, in _run
    self._context.run(self._callback, *self._args)
  File "/home/ppjet/Src/poezio/master/poezio/core/core.py", line 616, in on_input_readable
    self.do_command(replace_line_breaks(char), False)
  File "/home/ppjet/Src/poezio/master/poezio/core/core.py", line 775, in do_command
    self.tabs.current_tab.on_input(key, raw)
  File "/home/ppjet/Src/poezio/master/poezio/tabs/bookmarkstab.py", line 108, in on_input
    res = self.key_func[key]()                                      
  File "/home/ppjet/Src/poezio/master/poezio/tabs/bookmarkstab.py", line 57, in add_bookmark
    self.bookmarks_win.add_bookmark(new_bookmark)
  File "/home/ppjet/Src/poezio/master/poezio/windows/bookmark_forms.py", line 195, in add_bookmark
    get_theme().COLOR_NORMAL_TEXT)
  File "/home/ppjet/Src/poezio/master/poezio/windows/inputs.py", line 90, in set_color
    self.rewrite_text()                                             
  File "/home/ppjet/Src/poezio/master/poezio/windows/inputs.py", line 528, in rewrite_text
    self._win.erase()