Don't delete nested default lambda classes during inline transformation

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/LambdaInfo.kt

@@ -166,7 +166,7 @@ class DefaultLambda(
                 classReader.b,
                 invokeMethod.name,
                 invokeMethod.descriptor,
-                lambdaClassType)!!
+                lambdaClassType) ?: error("Can't find method '${invokeMethod.name}${invokeMethod.descriptor}' in '${classReader.className}'")
 
         if (needReification) {
             //nested classes could also require reification

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/MethodInliner.kt

@@ -165,7 +165,9 @@ class MethodInliner(
                     result.merge(transformResult)
                     result.addChangedType(oldClassName, newClassName)
 
-                    if (inliningContext.isInliningLambda && transformationInfo!!.canRemoveAfterTransformation()) {
+                    if (inliningContext.isInliningLambda &&
+                        inliningContext.lambdaInfo !is DefaultLambda && //never delete default lambda classes
+                        transformationInfo!!.canRemoveAfterTransformation()) {
                         // this class is transformed and original not used so we should remove original one after inlining
                         result.addClassToRemove(oldClassName)
                     }