file containing null byte causes crash about babi HOT 3 CLOSED

it should probably just reject these files -- similar to what it does for non-UTF-8 files

from babi.

it only comes up when trying to render the char, so opening the file with \x00 in it works (second case passes, since the display height is 80 lines) fine, as long as it is not rendered (first case).

@pytest.mark.parametrize('s', (b'\x00', b'\n' * 81 + b'\x00'))
def test_file_contains_zero_bytes(s, run, tmpdir):
    f = tmpdir.join('f')
    f.write_binary(s)
    with run(str(f)) as h, and_exit(h):
        h.press('a')
        h.await_text('*')
        h.press('^S')
        h.await_text('saved!')
        # h.await_text('error! zero byte found:')

It should probably display an error message like for non utf-8 files. So how can we catch this earlier, like when opening instead of when it's rendered? somewhere in babi.file.get_lines, but sio is IO[str] so we can't check b'\x00' in ... and a non byte string of '\x00' should still be allowed...

from babi.

here's where the other errors are checked:

from babi.