[FIR] Source for implicit iterator calls in for should not be null

^KT-62111 fixed


Merge-request: KT-MR-13029
Merged-by: Egor Kulikov <Egor.Kulikov@jetbrains.com>

compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopMissingLoopParameter.fir.kt

@@ -1,14 +1,14 @@
 fun useDeclaredVariables() {
-    for ((a, b)<!SYNTAX!><!>) {
+    <!ITERATOR_MISSING!>for ((a, b)<!SYNTAX!><!>) {
         a
         b
-    }
+    }<!>
 }
 
 fun checkersShouldRun() {
-    for ((@A a, _)<!SYNTAX!><!>) {
+    <!ITERATOR_MISSING!>for ((@A a, _)<!SYNTAX!><!>) {
 
-    }
+    }<!>
 }
 
 annotation class A

compiler/testData/diagnostics/tests/incompleteCode/checkNothingIsSubtype.fir.kt

@@ -10,6 +10,6 @@ fun test(nothing: Nothing?) {
 }
 
 fun sum(a : IntArray) : Int {
-for (n
-<!SYNTAX!>return<!><!SYNTAX!><!> "?"
+<!ITERATOR_MISSING!>for (n
+<!SYNTAX!>return<!><!SYNTAX!><!> "?"<!>
 <!NO_RETURN_IN_FUNCTION_WITH_BLOCK_BODY!>}<!>