Fix NPE in HLS deriveAudioFormat.

Issue:#5868
PiperOrigin-RevId: 247613811

RELEASENOTES.md

@@ -2,6 +2,8 @@
 
 ### dev-v2 (not yet released) ###
 
+* Fix NPE when using HLS chunkless preparation
+  ([#5868](https://github.com/google/ExoPlayer/issues/5868)).
 * Offline: Add option to remove all downloads.
 * Decoders:
   * Prefer codecs that advertise format support over ones that do not, even if

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsMediaPeriod.java

@@ -802,7 +802,7 @@ public final class HlsMediaPeriod implements MediaPeriod, HlsSampleStreamWrapper
       if (isPrimaryTrackInVariant) {
         channelCount = variantFormat.channelCount;
         selectionFlags = variantFormat.selectionFlags;
-        roleFlags = mediaTagFormat.roleFlags;
+        roleFlags = variantFormat.roleFlags;
         language = variantFormat.language;
         label = variantFormat.label;
       }