From 7327a6082db58a00ecd169a43f3fc3e0ea21e1a1 Mon Sep 17 00:00:00 2001
From: Till Kolter <till.kolter@gmail.com>
Date: Thu, 5 Dec 2024 16:36:45 +0100
Subject: [PATCH] fix: Leading whitespace chunks break partial parser

---
 src/lib/ChatCompletionStream.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/lib/ChatCompletionStream.ts b/src/lib/ChatCompletionStream.ts
index a88f8a23b..80bac5607 100644
--- a/src/lib/ChatCompletionStream.ts
+++ b/src/lib/ChatCompletionStream.ts
@@ -509,7 +509,9 @@ export class ChatCompletionStream<ParsedT = null>
         choice.message.content = (choice.message.content || '') + content;
 
         if (!choice.message.refusal && this.#getAutoParseableResponseFormat()) {
-          choice.message.parsed = partialParse(choice.message.content);
+          // Even a partial parser does not accept empty string
+          const trimmed = choice.message.content.trimStart();
+          choice.message.parsed = trimmed ? partialParse(trimmed) : null;
         }
       }