Fix leg assert and NPE to make BB green.

frog/leg/elements/elements.dart

Index: frog/leg/elements/elements.dart
===================================================================
--- frog/leg/elements/elements.dart	(revision 5433)
+++ frog/leg/elements/elements.dart	(working copy)
@@ -425,7 +425,8 @@
     // the compilation unit of the abstract element.
     if (getter !== null && getter.enclosingElement === enclosingElement) {
       return getter.position();
-    } else {
+    } else if (setter != null) {
+      // TODO(ahe): checking for null should not be necessary.

[ngeoffray, 2012/03/13 20:08:24]

Told you so :-)

[ahe, 2012/03/14 09:22:08]

Why is this happening? I think this is a symptom fix, that masks a different
bug.

The method [position] may not return null. That will lead to a crash in a
different place.

Take a look at this code in ContainerElement.addGetterOrSetter:

      AbstractFieldElement field = new AbstractFieldElement(element.name, this);
      addMember(field, listener);
      if (element.kind == ElementKind.GETTER) {
        field.getter = element;
      } else {
        field.setter = element;
      }

I think the problem is that [addMember] is called before the
AbstractFieldElement is set up correctly, and you will find that the error
message is not indicating the correct location.

       return setter.position();
     }

[floitsch, 2012/03/14 09:03:09]

else { return null; }

   }