Login error messages

I can easily change the login error messages in the ‘action-login.php’ file, but I would really like to avoid editing the plugin files. Is there anyway to change those error messages without modifying this file?

I would like to have a different error message if the username OR password is NOT filled out. Currently the message ‘We need some input values to handle the login.’ is present. I would like it to say “Please enter your username” or “Please enter your password” to be more specific. Is this possible?

https://wordpress.org/plugins/user-frontend/