Fix checking imaAdMediaInfo nullness

It's intended to log a warning in this case, rather than throw.

Issue: #8290

#minor-release

PiperOrigin-RevId: 347790527

RELEASENOTES.md

@@ -52,6 +52,9 @@
         ([#3750](https://github.com/google/ExoPlayer/issues/3750)).
     *   Fix a condition where playback can get stuck before an empty ad
         ([#8205](https://github.com/google/ExoPlayer/issues/8205)).
+    *   Log a warning rather than throwing when reaching the end of the stream
+        with an ad playing but without ad media info
+        ([#8290](https://github.com/google/ExoPlayer/issues/8290)).
     *   Add `ImaAdsLoader.Builder.setEnableContinuousPlayback` for setting
         whether to request ads for continuous playback.
 *   Metadata retriever:

extensions/ima/src/main/java/com/google/android/exoplayer2/ext/ima/AdTagLoader.java

@@ -800,7 +800,7 @@ import java.util.Map;
         && playWhenReady) {
       ensureSentContentCompleteIfAtEndOfStream();
     } else if (imaAdState != IMA_AD_STATE_NONE && playbackState == Player.STATE_ENDED) {
-      AdMediaInfo adMediaInfo = checkNotNull(imaAdMediaInfo);
+      @Nullable AdMediaInfo adMediaInfo = imaAdMediaInfo;
       if (adMediaInfo == null) {
         Log.w(TAG, "onEnded without ad media info");
       } else {