data tree MAINTENANCE improve error on inner node creation

Because list must be created with another
function.
diff --git a/src/tree_data.c b/src/tree_data.c
index 7161054..d22183a 100644
--- a/src/tree_data.c
+++ b/src/tree_data.c
@@ -764,7 +764,7 @@
     }
 
     schema = lys_find_child(parent ? parent->schema : NULL, module, name, 0, LYS_CONTAINER | LYS_NOTIF | LYS_RPC | LYS_ACTION, 0);
-    LY_CHECK_ERR_RET(!schema, LOGERR(ctx, LY_EINVAL, "Inner node \"%s\" not found.", name), NULL);
+    LY_CHECK_ERR_RET(!schema, LOGERR(ctx, LY_EINVAL, "Inner node (and not a list) \"%s\" not found.", name), NULL);
 
     if (!lyd_create_inner(schema, &ret) && parent) {
         lyd_insert_node(parent, NULL, ret);