Fix bug with member extensions with explicit receiver

Co-authored-by: Ilya Kirillov <ilya.kirillov@jetbrains.com>

idea/idea-completion/testData/basic/common/primitiveCompletion/implicitReceiverCompletion.kt

@@ -5,13 +5,10 @@ class A {
 
 fun A.run(action: A.() -> Unit) {}
 
-fun test(a: A) {
+fun test() {
+    val a = A()
     a.run {
-
         <caret>
-
-        // remove this
-        Unit
     }
 }