Fix movie library crash

[cewert]

Ensure animation node is valid before using to prevent app crash. This comes from the roku crash log.

Crashlog:

'Dot' Operator attempted with invalid BrightScript Component or interface reference. (runtime error &hec) in pkg:/components/ItemGrid/MovieLibraryView.brs(703) 
Backtrace: 
#0  Function swapdone() As Voi$1 file/line: pkg:/components/ItemGrid/MovieLibraryView.brs(703) 
Local Variables: 
global           Interface:ifGloba$1 m                roAssociativeArray refcnt=2 count:2

which points to this line after running build-prod on 2.1.1:

if m.swapAnimation.state = "stopped"

Issues

Ref #1164