animation: don't NULL deref if _run() returns NULL
animation: don't NULL deref if _run() returns NULL

Signed-off-by: U. Artie Eoff <32aece0d55055227b44d04b7d0051cf3d04ee871@intel.com>

Fantu/compositor-spice,xorgy/weston,eyolfson/weston,giucam/weston,Gnurou/weston,xorgy/weston,giucam/weston,krezovic/weston,eyolfson/weston,Tarnyko/weston-xdg_surface_present,krezovic/weston,jonnylamb/weston,Fantu/compositor-spice,udoprog/weston,kwm81/weston,Gnurou/weston,sir-murray/weston,kwm81/weston,Tarnyko/weston-xdg_surface_present,jonnylamb/weston,Fantu/compositor-spice,mchalupa/weston,mchalupa/weston,sir-murray/weston,udoprog/weston