Avoid swallowing exceptions when switching AssetLoader

Exceptions thrown when switching AssetLoader were not reported through
the error listener. Therefore, the resources were not released and the
export was not ending.

PiperOrigin-RevId: 530626300

library/transformer/src/main/java/com/google/android/exoplayer2/transformer/SequenceAssetLoader.java

@@ -470,6 +470,7 @@ import java.util.concurrent.atomic.AtomicInteger;
     private void switchAssetLoader() {
       handler.post(
           () -> {
+            try {
               addCurrentProcessedInput();
               totalDurationUs += currentAssetDurationUs;
               currentAssetLoader.release();
@@ -486,6 +487,10 @@ import java.util.concurrent.atomic.AtomicInteger;
                       checkNotNull(Looper.myLooper()),
                       /* listener= */ SequenceAssetLoader.this);
               currentAssetLoader.start();
+            } catch (RuntimeException e) {
+              onError(
+                  ExportException.createForAssetLoader(e, ExportException.ERROR_CODE_UNSPECIFIED));
+            }
           });
     }