parser xml BUGFIX opaque node without a namespace (#2181)

Co-authored-by: zhangtao 00621101 <zhangtao387@huawei.com>
diff --git a/src/parser_xml.c b/src/parser_xml.c
index 4fb7187..6978475 100644
--- a/src/parser_xml.c
+++ b/src/parser_xml.c
@@ -481,7 +481,7 @@
         opaq = (struct lyd_node_opaq *)first;
         assert(opaq->format == LY_VALUE_XML);
         if (!ly_strncmp(opaq->name.name, name, name_len) &&
-                ((ns && !strcmp(opaq->name.module_ns, ns)) || (!ns && !opaq->name.module_ns))) {
+                ((ns && opaq->name.module_ns && !strcmp(opaq->name.module_ns, ns)) || (!ns && !opaq->name.module_ns))) {
             if (opaq->value && opaq->value[0]) {
                 /* leaf-list nodes */
                 opaq->hints |= LYD_NODEHINT_LEAFLIST;