Dunstify can pass empty appname to libnotify

[gregdan3]

Issue Description

Any of the following arguments to dunstify will pass an empty appname to libnotify:

• --appname=
• --appname ""
• --appname=""

All of these result in the following error:

gregdan3@Theros ~/dunst (master)> ./dunstify --appname ""

(dunstify:270468): libnotify-CRITICAL **: 09:19:40.827: notify_init: assertion '*app_name != '\0'' failed
Unable to initialize libnotify

Installation info

• Version:

  • Dunst - A customizable and lightweight notification-daemon 1.5.0 (2020-07-23)
  • Dunst - A customizable and lightweight notification-daemon v1.5.0-12-g0467e46

• Install type:

  • Package
  • Manual

• Distro and version: Archlinux