Fix MovieDetails crash (3)

[cewert]

Validate animation node exists before using to prevent 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/movies/MovieDetails.brs(51) 
Backtrace: 
#0  Function onmovieposterswapanimationstatechange() As Voi$1 file/line: pkg:/components/movies/MovieDetails.brs(51) 
Local Variables: 
global           Interface:ifGloba$1 m                roAssociativeArray refcnt=2 count:2

which points to this line after running build-prod on 2.1.2:

if LCase(m.moviePosterSwapAnimation.state) <> "stopped" then

Issues

Ref #1164