Implement scene-based chapter quest progression

src/services/llmClient.ts

@@ -46,7 +46,11 @@ function logLlmDebug(title: string, payload: unknown) {
 }
 
 function normalizeLlmError(error: unknown): never {
-  if (error instanceof DOMException && error.name === 'AbortError') {
+  if (
+    typeof DOMException !== 'undefined'
+    && error instanceof DOMException
+    && error.name === 'AbortError'
+  ) {
     throw new LlmTimeoutError('The LLM request timed out. Please check the network or endpoint.');
   }