Handle functions with no attached node in find_position_visitor.

pkg/dartino_compiler/lib/src/find_position_visitor.dart

Index: pkg/dartino_compiler/lib/src/find_position_visitor.dart
diff --git a/pkg/dartino_compiler/lib/src/find_position_visitor.dart b/pkg/dartino_compiler/lib/src/find_position_visitor.dart
index 72e62ca43cd7496f4a09842ac40bcb0cd7590827..d1656a12b4267376ea432959d4a631bf1bb5975d 100644
--- a/pkg/dartino_compiler/lib/src/find_position_visitor.dart
+++ b/pkg/dartino_compiler/lib/src/find_position_visitor.dart
@@ -67,6 +67,8 @@ class FindFunctionAtPositionVisitor extends BaseElementVisitor {
   visitElement(Element element, _) {}
 
   bool containsPosition(Node node) {
+    // TODO(sigurdm): Find out when [node] is null.
+    if (node == null) return false;

[danrubel, 2016/07/12 14:15:06]

Should we log something here to obtain more information?
Print a warning and info for the user to pass along to us but don't crash?

[sigurdm, 2016/08/10 09:05:11]

I prefer that we replicate it locally and fix it.

     return node.getBeginToken().charOffset <= position &&
         position < node.getEndToken().charEnd;
   }