Fix a wrong return value in previous patch
diff --git a/xmlreader.c b/xmlreader.c
index ef41927..c5ab60e 100644
--- a/xmlreader.c
+++ b/xmlreader.c
@@ -5625,7 +5625,7 @@
     if (input == NULL) {
         if (ioclose != NULL)
             ioclose(ioctx);
-        return (NULL);
+        return (-1);
     }
     return (xmlTextReaderSetup(reader, input, URL, encoding, options));
 }