fix(search): use correct callback signature for error logging

The custom ajax `.then(success, error)` passes `(event, responseStatus)`
not a standard Error. Use the response status for a more useful warning
message, e.g. "(404)" instead of logging a ProgressEvent object.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Bowl42

src/plugins/search/search.js

@@ -338,8 +338,8 @@ export async function init(config, vm) {
           await saveData(config.maxAge, expireKey);
         }
       },
-      async error => {
-        console.warn(`[Docsify] Failed to fetch ${path} for search indexing`, error);
+      async (_event, response) => {
+        console.warn(`[Docsify] Failed to fetch ${path} for search indexing (${response?.status || 'network error'})`);
         if (len === ++count) {
           await saveData(config.maxAge, expireKey);
         }