diff --git a/src/lib/server/tools/lyrics.ts b/src/lib/server/tools/lyrics.ts
index 751b798..52160ba 100644
--- a/src/lib/server/tools/lyrics.ts
+++ b/src/lib/server/tools/lyrics.ts
@@ -3,9 +3,9 @@ import type { LyricLine, LyricSegment } from '../../types'
 import { isKana, isKanji } from 'wanakana'
 
 // Please put OPENROUTER_API_KEY in your environment variables.
-if (!process.env.OPENROUTER_API_KEY) throw new Error('Please set OPENROUTER_API_KEY in your environment variables.')
+if (!process.env.OPENROUTER_API_KEY) console.warn('Please set OPENROUTER_API_KEY in your environment variables.')
 const client = new OpenRouter({
-  apiKey: process.env.OPENROUTER_API_KEY!
+  apiKey: process.env.OPENROUTER_API_KEY ?? ""
 })
 const req = {
   model: "openai/gpt-5-mini",