Misc small fixes in Transformer.

PiperOrigin-RevId: 420056876

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

@@ -97,7 +97,6 @@ public final class Transformer {
     private boolean removeAudio;
     private boolean removeVideo;
     private String containerMimeType;
-    // TODO(b/204869912): Make final once deprecated setters are removed.
     private TransformationRequest transformationRequest;
     private Transformer.Listener listener;
     private DebugViewProvider debugViewProvider;

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

@@ -77,7 +77,7 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
     }
     Format inputFormat = checkNotNull(formatHolder.format);
     String sampleMimeType = checkNotNull(inputFormat.sampleMimeType);
-    if (transformationRequest.audioMimeType == null
+    if (transformationRequest.videoMimeType == null
         && !muxerWrapper.supportsSampleMimeType(sampleMimeType)) {
       throw TransformationException.createForMuxer(
           new IllegalArgumentException(