fix build error

server/src/adminApi.ts

@@ -1014,7 +1014,7 @@ adminRouter.post("/admin/namemanager/import", async (req: Request, res: Response
     console.error('[AdminAPI] Error importing nameManager state:', error);
     
     // Handle specific error types
-    if (error.message && error.message.includes('PayloadTooLargeError')) {
+    if (error instanceof Error && error.message && error.message.includes('PayloadTooLargeError')) {
       return res.status(413).json({ 
         error: 'File too large', 
         details: 'The save file is too large to process. Maximum size: 50MB' 
@@ -1023,7 +1023,7 @@ adminRouter.post("/admin/namemanager/import", async (req: Request, res: Response
     
     res.status(500).json({ 
       error: 'Failed to import nameManager state', 
-      details: error.message 
+      details: error instanceof Error ? error.message : 'Unknown error'
     });
   }
 });