parser UPDATE guess opaque node schema nodes

... for their descendant parsing purposes.

Refs #2086
diff --git a/tests/utests/data/test_parser_json.c b/tests/utests/data/test_parser_json.c
index e5513da..e9619e2 100644
--- a/tests/utests/data/test_parser_json.c
+++ b/tests/utests/data/test_parser_json.c
@@ -584,7 +584,7 @@
 
     /* empty name */
     PARSER_CHECK_ERROR("{\"@a:foo\":{\"\":0}}", 0, LYD_VALIDATE_PRESENT, tree, LY_EVALID,
-            "JSON object member name cannot be a zero-length string.", "Line number 1.");
+            "JSON object member name cannot be a zero-length string.", "Data location \"/@a:foo\", line number 1.");
 
     /* opaque data tree format print */
     data =