parser json BUGFIX skip unknown meta for data nodes

Fixes #1770
diff --git a/src/parser_json.c b/src/parser_json.c
index 355b544..5408279 100644
--- a/src/parser_json.c
+++ b/src/parser_json.c
@@ -793,7 +793,7 @@
                 ret = LY_EVALID;
                 goto cleanup;
             }
-            if (!(lydctx->parse_opts & LYD_PARSE_OPAQ)) {
+            if (node->schema) {
                 /* skip element with children */
                 ret = lydjson_data_skip(lydctx->jsonctx);
                 LY_CHECK_GOTO(ret, cleanup);
@@ -801,6 +801,7 @@
                 /* end of the item */
                 continue;
             }
+            assert(lydctx->parse_opts & LYD_PARSE_OPAQ);
         }
 
         /* get the value */