do not try to calculate procent sum if there was an error

src/http/modules/ngx_http_split_clients_module.c

diff --git a/src/http/modules/ngx_http_split_clients_module.c b/src/http/modules/ngx_http_split_clients_module.c
index 95286ae..c28b8f9 100644
--- a/src/http/modules/ngx_http_split_clients_module.c
+++ b/src/http/modules/ngx_http_split_clients_module.c
@@ -163,6 +163,10 @@
 
     *cf = save;
 
+    if (rv != NGX_CONF_OK) {
+        return rv;
+    }
+
     sum = 0;
     last = 0;
     part = ctx->parts.elts;