Null pointer exception fixed

pesPayloadReader can be null here because DefaultStreamReader.init() can return null on unknown streamId. If we have a junk transport stream in our content an exception will be thrown.

library/src/main/java/com/google/android/exoplayer2/extractor/ts/TsExtractor.java

@@ -467,8 +467,10 @@ public final class TsExtractor implements Extractor {
           pesPayloadReader = id3Reader;
         } else {
           pesPayloadReader = streamReaderFactory.createStreamReader(streamType, esInfo);
+          if (pesPayloadReader != null) {
             pesPayloadReader.init(output, new TrackIdGenerator(trackId, MAX_PID_PLUS_ONE));
           }
+        }
 
         if (pesPayloadReader != null) {
           tsPayloadReaders.put(elementaryPid, new PesReader(pesPayloadReader, timestampAdjuster));