on resize - chgat() returns ERR when query is an empty string

[mtshrmn]

How to recreate:

1. search for nothing (press on / and then return)
2. resize

for some reason this doesn't crash on specific chapters (or vise versa, crashes on specific pages).

Traceback:

Traceback (most recent call last):
  File "/home/suerflowz/.local/bin/nuber", line 8, in <module>
    sys.exit(main())
  File "/home/suerflowz/.local/lib/python3.10/site-packages/click/core.py", line 1128, in __call__
    return self.main(*args, **kwargs)
  File "/home/suerflowz/.local/lib/python3.10/site-packages/click/core.py", line 1053, in main
    rv = self.invoke(ctx)
  File "/home/suerflowz/.local/lib/python3.10/site-packages/click/core.py", line 1395, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/suerflowz/.local/lib/python3.10/site-packages/click/core.py", line 754, in invoke
    return __callback(*args, **kwargs)
  File "/home/suerflowz/.local/lib/python3.10/site-packages/nuber/__init__.py", line 18, in main
    reader.loop() # type: ignore
  File "/home/suerflowz/.local/lib/python3.10/site-packages/ueberzug/lib/v0/__init__.py", line 378, in decorator
    return function(*args, canvas=self, **kwargs)
  File "/home/suerflowz/.local/lib/python3.10/site-packages/nuber/reader.py", line 434, in loop
    self.on_key(ch, canvas)
  File "/home/suerflowz/.local/lib/python3.10/site-packages/nuber/reader.py", line 388, in on_key
    action(canvas)
  File "/home/suerflowz/.local/lib/python3.10/site-packages/nuber/reader.py", line 362, in action_resize
    self.highlight_query()
  File "/home/suerflowz/.local/lib/python3.10/site-packages/nuber/reader.py", line 164, in highlight_query
    self.pad.chgat(row + row_offset, start_col, chars_len, f)
_curses.error: chgat() returned ERR