dont use a thread for I/O with kitten

kitty/fonts/list.py

@@ -30,9 +30,6 @@ def as_json(indent: Optional[int] = None) -> str:
     return json.dumps(groups, indent=indent)
 
 
-exception_in_io_handler: Optional[Exception] = None
-
-
 def handle_io(from_kitten: BinaryIO, to_kitten: BinaryIO) -> None:
     import json
     global exception_in_io_handler
@@ -42,22 +39,17 @@ def handle_io(from_kitten: BinaryIO, to_kitten: BinaryIO) -> None:
         to_kitten.write(b'\n')
         to_kitten.flush()
 
-    try:
-        send_to_kitten(create_family_groups(add_variable_data=True))
-        for line in from_kitten:
-            cmd = json.loads(line)
-            action = cmd['action']
-            if action == 'ping':
-                send_to_kitten({'action': 'pong'})
-    except Exception as e:
-        exception_in_io_handler = e
+    send_to_kitten(create_family_groups(add_variable_data=True))
+    for line in from_kitten:
+        cmd = json.loads(line)
+        action = cmd['action']
+        if action == 'ping':
+            send_to_kitten({'action': 'pong'})
 
 
 def main(argv: Sequence[str]) -> None:
     import os
     import subprocess
-    import sys
-    from threading import Thread
 
     from kitty.constants import kitten_exe
     argv = list(argv)
@@ -67,9 +59,12 @@ def main(argv: Sequence[str]) -> None:
     if os.environ.get('KITTY_STDIO_FORWARDED'):
         pass_fds.append(int(os.environ['KITTY_STDIO_FORWARDED']))
     p = subprocess.Popen([kitten_exe(), '__list_fonts__'], stdin=subprocess.PIPE, stdout=subprocess.PIPE, pass_fds=pass_fds)
-    Thread(target=handle_io, args=(p.stdout, p.stdin), daemon=True).start()
     try:
-        raise SystemExit(p.wait())
-    finally:
-        if exception_in_io_handler is not None:
-            print(exception_in_io_handler, file=sys.stderr)
+        handle_io(p.stdout, p.stdin)
+    except Exception:
+        ret = p.wait()
+        import traceback
+        traceback.print_exc()
+    else:
+        ret = p.wait()
+    raise SystemExit(ret)

tools/cmd/list_fonts/main.go

@@ -22,6 +22,20 @@ func json_decode(v any) error {
 	return nil
 }
 
+func to_kitty(v any) error {
+	data, err := json.Marshal(v)
+	if err != nil {
+		return fmt.Errorf("Could not encode message to kitty with error: %w", err)
+	}
+	if _, err = os.Stdout.Write(data); err != nil {
+		return fmt.Errorf("Failed to send message to kitty with I/O error: %w", err)
+	}
+	if _, err = os.Stdout.WriteString("\n"); err != nil {
+		return fmt.Errorf("Failed to send message to kitty with I/O error: %w", err)
+	}
+	return nil
+}
+
 func main() (rc int, err error) {
 	json_decoder = json.NewDecoder(os.Stdin)
 	lp, err := loop.New()