From e4188c4ba443a21d1ef94658df5366f80f0e573b Mon Sep 17 00:00:00 2001
From: Robert Craigie <robert@craigie.dev>
Date: Fri, 13 Sep 2024 16:15:28 +0100
Subject: [PATCH] fix(examples): handle usage chunk in tool call streaming
 (#1068)

---------

Co-authored-by: Jacob Zimmerman <jacob@stainlessapi.com>
---
 examples/tool-calls-stream.ts | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/examples/tool-calls-stream.ts b/examples/tool-calls-stream.ts
index 924e6b7cf..687ea86fd 100755
--- a/examples/tool-calls-stream.ts
+++ b/examples/tool-calls-stream.ts
@@ -184,7 +184,13 @@ function messageReducer(previous: ChatCompletionMessage, item: ChatCompletionChu
     }
     return acc;
   };
-  return reduce(previous, item.choices[0]!.delta) as ChatCompletionMessage;
+
+  const choice = item.choices[0];
+  if (!choice) {
+    // chunk contains information about usage and token counts
+    return previous;
+  }
+  return reduce(previous, choice.delta) as ChatCompletionMessage;
 }
 
 function lineRewriter() {