fix error log message

src/http/modules/ngx_http_log_module.c

diff --git a/src/http/modules/ngx_http_log_module.c b/src/http/modules/ngx_http_log_module.c
index caa1efd..3d8730a 100644
--- a/src/http/modules/ngx_http_log_module.c
+++ b/src/http/modules/ngx_http_log_module.c
@@ -797,7 +797,10 @@
         if (fmt[i].name.len == value[1].len
             && ngx_strcmp(fmt[i].name.data, value[1].data) == 0)
         {
-            return "duplicate \"log_format\" name";
+            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                               "duplicate \"log_format\" name \"%V\"",
+                               &value[1]);
+            return NGX_CONF_ERROR;
         }
     }