$ grep -ri DEFAULT_SOUND *
config.py:DEFAULT_SOUND_PATH = '/usr/share/sounds/gtk-events/clicked.wav'
$ aplay /usr/share/sounds/gtk-events/clicked.wav
/usr/share/sounds/gtk-events/clicked.wav: No such file or directory
So basically, the timer-applet has a dependency on a file which doesn't ship in that package and which is also not accounted for in any of the package dependencies list for the timer-applet package.
Ah, here is the problem:
$ grep -ri DEFAULT_SOUND * py:DEFAULT_ SOUND_PATH = '/usr/share/ sounds/ gtk-events/ clicked. wav' sounds/ gtk-events/ clicked. wav sounds/ gtk-events/ clicked. wav: No such file or directory
config.
$ aplay /usr/share/
/usr/share/
So basically, the timer-applet has a dependency on a file which doesn't ship in that package and which is also not accounted for in any of the package dependencies list for the timer-applet package.