[BUG] cursive exits immediately when asked to display a string with a null byte

[janstarke]

Describe the bug

cursive programs exit immediately when asked to display a string with a null byte. No error message is shown, and there doesn't seem to be a panic

To Reproduce

MWE:
This program should display a TextView, but instead it exists without any complaint.

use cursive::{views::TextView, Cursive, CursiveExt};

fn main() {
    let mut app = Cursive::new();
    app.add_layer(TextView::new("Hello Nullbyte: \0"));
    app.add_global_callback('q', |a| a.quit());
    app.run();
}

Expected behavior
This program should display a TextView, or at least panic with an error message, so that users of cursive know that null bytes are not allowed

Screenshots
no screenshot available

Environment

• Ubuntu Linux
• Backend used: ncurses (the default one)
• de_DE.UTF-8
• 0.20.0

Additional context
I found this while fixing janstarke/regview#8

[gyscos]

The crash should now be fixed with the latest commit, which ignores \0 (when using unicode-width < 0.1.13), or replaces it with � (when using unicode-width >= 0.1.13).

Note that on my terminal, the handling of � is a bit buggy: it is treated as a single-width character, but is rendered as a double-width one: this is on Alacritty 0.13.2:

The same happens on gnone-terminal. Might depend on the font used. This happens both with monospace and with Source code pro. Ah - with Ubuntu Mono it looks good! On a macOS terminal with the default font, it also looks properly single-width. 🤷