FsEventWatcher crashes when dealing with empty path

[kkolyan]

System details

• OS/Platform name and version: Macos Ventura 13.4.1 (22F82), M1
• Rust version (if building from source): rustc --version: rustc 1.81.0 (eeb90cda1 2024-09-04)
• Notify version (or commit hash if building from git): 6.1.1

What you did (as detailed as you can)

1. create empty cargo bin project (I created it in /Users/kkolyan/dev/rust/notify_crash directory, if that matters)
2. add following to Cargo.toml dependencies section:

notify: 6.1.1

3. set following code to main.rs

main.rs:
```rs
use std::{path::PathBuf, sync::atomic::{AtomicBool, Ordering}};

use notify::{EventKind, FsEventWatcher, Watcher};

fn main() {
    let need_refresh_flag = AtomicBool::new(false);
    let mut watcher: FsEventWatcher = notify::recommended_watcher(move |event: notify::Result<notify::Event>| {
        if let Ok(event) = event {
            if let EventKind::Modify(_) | EventKind::Create(_) | EventKind::Remove(_) =
                event.kind
            {
                need_refresh_flag.store(true, Ordering::Relaxed);
            }
        }
    }).unwrap();
    let path: PathBuf = Default::default();
    let _ = watcher.unwatch(&path);
    println!("It's ok");
}

4. cargo run

What you expected

Program normally returns

What happened

It crashes with segmentation fault