get '/' => sub {
  # template 'index';
  send_error("Not authorized", 401);
};

When running with bin/app.pl directly, the message "Not authorized" can be displayed in the web.
But if I run it with starman:

plackup -E deployment -s Starman --workers=10 -l 0.0.0.0:3000 -D --access-log=logs/access.log -a bin/app.pl

This error message seems lost.
Do you know how to fix up it?
b/c I wrote the API with dancer, I need to tell the clients what are the errors.

Thanks.