return NULL instead of NGX_CONF_ERROR on a create conf failure
diff --git a/src/core/ngx_cycle.c b/src/core/ngx_cycle.c
index 47d5f56..63eec14 100644
--- a/src/core/ngx_cycle.c
+++ b/src/core/ngx_cycle.c
@@ -216,7 +216,7 @@
 
         if (module->create_conf) {
             rv = module->create_conf(cycle);
-            if (rv == NGX_CONF_ERROR) {
+            if (rv == NULL) {
                 ngx_destroy_pool(pool);
                 return NULL;
             }