Visit kotlin lambda function with null if backing has been removed

This will ensure that no errors are thrown and reported as warnings when
rewriting kotlin metadata.

Bug: 194915678
Bug: 195757160
Change-Id: Id23f7cac2280a999c1ad3d5a4560b0f2d408fb48
diff --git a/src/main/java/com/android/tools/r8/kotlin/KotlinLambdaInfo.java b/src/main/java/com/android/tools/r8/kotlin/KotlinLambdaInfo.java
index 7a4fc78..c8cb4d6 100644
--- a/src/main/java/com/android/tools/r8/kotlin/KotlinLambdaInfo.java
+++ b/src/main/java/com/android/tools/r8/kotlin/KotlinLambdaInfo.java
@@ -78,7 +78,6 @@
           .options()
           .reporter
           .info(KotlinMetadataDiagnostic.lambdaBackingNotFound(clazz.type, function.getName()));
-      return false;
     }
     return function.rewrite(visitorProvider.get()::visitFunction, backing, appView, namingLens);
   }