Refine cc7f0e2d83

getDispatchReceiver/getExtensionReceiver always return not-null value,
but in the absence of receiver this value is equal StackValue.none(), i.e.
has a size 1

The tests were passing because of the problems with the test framework:
4b9e20ab8c

compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java

@@ -2945,8 +2945,8 @@ public class ExpressionCodegen extends KtVisitor<StackValue, StackValue> impleme
             if (isSuspensionPoint && isSafeCallOrOnStack) {
                 boolean bothReceivers =
                         receiver instanceof StackValue.CallReceiver
-                        && ((StackValue.CallReceiver) receiver).getDispatchReceiver() != null
+                        && ((StackValue.CallReceiver) receiver).getDispatchReceiver().type.getSort() != Type.VOID
-                        && ((StackValue.CallReceiver) receiver).getExtensionReceiver() != null;
+                        && ((StackValue.CallReceiver) receiver).getExtensionReceiver().type.getSort() != Type.VOID;
                 Type firstReceiverType =
                         bothReceivers
                         ? ((StackValue.CallReceiver) receiver).getDispatchReceiver().type

compiler/backend/src/org/jetbrains/kotlin/codegen/StackValue.java

@@ -1597,10 +1597,12 @@ public abstract class StackValue {
             AsmUtil.dup(v, extensionReceiver.type, dispatchReceiver.type);
         }
 
+        @NotNull
         public StackValue getDispatchReceiver() {
             return dispatchReceiver;
         }
 
+        @NotNull
         public StackValue getExtensionReceiver() {
             return extensionReceiver;
         }