Fix internal error when assigning a type to a value (#26517)

Fixes an internal error when trying to assign a type to a value inside a
task intent.

Resolves #26511

- [x] full paratest with/without gasnet

[Reviewed by @mppf]

compiler/resolution/functionResolution.cpp

@@ -9175,9 +9175,9 @@ static void moveHaltMoveIsUnacceptable(CallExpr* call) {
   } else {
     if (lhsSym->hasFlag(FLAG_TYPE_VARIABLE) == false &&
         lhsSym->hasFlag(FLAG_MAYBE_TYPE)    == false) {
-      FnSymbol* fn = toFnSymbol(call->parentSymbol);
 
-      if (fn->getReturnSymbol() == lhsSym) {
+      auto fn = toFnSymbol(call->parentSymbol);
+      if (fn && fn->getReturnSymbol() == lhsSym) {
         USR_FATAL(call, "illegal return of type where value is expected");
 
       } else if (lhsSym->hasFlag(FLAG_CHPL__ITER) == true) {

test/classes/deitz/types/type_to_value_error_intent.chpl

@@ -0,0 +1,10 @@
+class C {
+  var x: int;
+}
+
+var c: borrowed C?;
+
+forall 1..10 with (var c = C()) {
+}
+
+writeln(c);

test/classes/deitz/types/type_to_value_error_intent.good

@@ -0,0 +1 @@
+type_to_value_error_intent.chpl:7: error: illegal assignment of type to value