NullPointerException for subtitles of DASH content

[ChernyshovYuriy]

There is NullPointerException when select subtitles of the DASH content.
URL to test (clear DASH):

http://bitmovin-a.akamaihd.net/content/sintel/sintel.mpd

Steps:

• run ExoPlayer test application with provided URL
• once video started, select any subtitle track and press OK
• observe NullPointerException

Stacktrace:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.exoplayer2.Format[] com.google.android.exoplayer2.source.chunk.ChunkExtractorWrapper.getSampleFormats()' on a null object reference
                          at com.google.android.exoplayer2.source.dash.DefaultDashChunkSource.getNextChunk(DefaultDashChunkSource.java:188)
                          at com.google.android.exoplayer2.source.chunk.ChunkSampleStream.continueLoading(ChunkSampleStream.java:327)
                          at com.google.android.exoplayer2.source.CompositeSequenceableLoader.continueLoading(CompositeSequenceableLoader.java:55)
                          at com.google.android.exoplayer2.source.dash.DashMediaPeriod.continueLoading(DashMediaPeriod.java:196)
                          at com.google.android.exoplayer2.ExoPlayerImplInternal.maybeContinueLoading(ExoPlayerImplInternal.java:1301)
                          at com.google.android.exoplayer2.ExoPlayerImplInternal.reselectTracksInternal(ExoPlayerImplInternal.java:808)
                          at com.google.android.exoplayer2.ExoPlayerImplInternal.handleMessage(ExoPlayerImplInternal.java:328)
                          at android.os.Handler.dispatchMessage(Handler.java:98) 
                          at android.os.Looper.loop(Looper.java:154) 
                          at android.os.HandlerThread.run(HandlerThread.java:61) 
                          at com.google.android.exoplayer2.util.PriorityHandlerThread.run(PriorityHandlerThread.java:40) 

My notes:
Simple null pointer check solves problem.
Current in market code:

if (representationHolder.extractorWrapper.getSampleFormats() == null) {
      pendingInitializationUri = selectedRepresentation.getInitializationUri();
    }

changes applied in order to avoid NullPointerException:

if (representationHolder.extractorWrapper == null || representationHolder.extractorWrapper.getSampleFormats() == null) {
      pendingInitializationUri = selectedRepresentation.getInitializationUri();
    }