diff --git a/tools/server/webui/src/utils/app.context.tsx b/tools/server/webui/src/utils/app.context.tsx
index 0b95e88f89376..ad59b82ee8064 100644
--- a/tools/server/webui/src/utils/app.context.tsx
+++ b/tools/server/webui/src/utils/app.context.tsx
@@ -255,7 +255,7 @@ export const AppContextProvider = ({
         if (chunk.error) {
           throw new Error(chunk.error?.message || 'Unknown error');
         }
-        const addedContent = chunk.choices[0].delta.content;
+        const addedContent = chunk.choices?.[0].delta.content;
         const lastContent = pendingMsg.content || '';
         if (addedContent) {
           pendingMsg = {