trying to fix #129692 xmlTextReaderExpand() when using an

* xmlreader.c: trying to fix #129692 xmlTextReaderExpand() when
  using an xmlReaderWalker()
Daniel
diff --git a/xmlreader.c b/xmlreader.c
index 485859e..bfcc053 100644
--- a/xmlreader.c
+++ b/xmlreader.c
@@ -1482,10 +1482,12 @@
  */
 xmlNodePtr
 xmlTextReaderExpand(xmlTextReaderPtr reader) {
-    if ((reader == NULL) || (reader->node == NULL) || (reader->ctxt == NULL))
+    if ((reader == NULL) || (reader->node == NULL))
         return(NULL);
     if (reader->doc != NULL)
         return(reader->node);
+    if (reader->ctxt == NULL)
+        return(NULL);
     if (xmlTextReaderDoExpand(reader) < 0)
         return(NULL);
     return(reader->node);