Add panic handler hook to exit alternative screen and raw mode

src/main.rs

@@ -21,7 +21,7 @@ use std::{
     env::args,
     ffi::OsString,
     fs::{File, OpenOptions},
-    io::{stdout, Read, Stdout, Write},
+    io::{Read, Stdout, Write},
     os::fd::FromRawFd,
     path::{Path, PathBuf},
     sync::Arc,
@@ -459,11 +459,28 @@ fn main() -> Result<()> {
     });
 
     let state = State::from_str(file_name, &text)?;
-    let mut stdout = stdout();
+
+    // begin to enter alternate screen
+    let mut stdout = std::io::stdout();
     terminal::enable_raw_mode()?;
     stdout.queue(terminal::EnterAlternateScreen)?;
+
+    // register a panic handler to exit the alternate screen
+    let old_panic_handler = std::panic::take_hook();
+    std::panic::set_hook(Box::new(move |info| {
+        let mut stdout = std::io::stdout();
+        let _ = stdout.queue(terminal::LeaveAlternateScreen);
+        let _ = terminal::disable_raw_mode();
+        let _ = stdout.flush();
+        old_panic_handler(info)
+    }));
+
+    // run inner event loop
     let result = screen_main(&mut stdout, state);
+
+    // exit alternate screen
     stdout.queue(terminal::LeaveAlternateScreen)?;
     terminal::disable_raw_mode()?;
+
     result
 }