fix(ChatCompletionStream): abort on async iterator break and handle errors (#699)

`break`-ing the async iterator did not previously abort the request which increases usage.
Errors are now handled more effectively in the async iterator.

Author: stainless-bot

src/lib/ChatCompletionRunFunctions.test.ts

@@ -1,5 +1,5 @@
 import OpenAI from 'openai';
-import { OpenAIError } from 'openai/error';
+import { OpenAIError, APIConnectionError } from 'openai/error';
 import { PassThrough } from 'stream';
 import {
   ParsingToolFunction,
@@ -2207,6 +2207,7 @@ describe('resource completions', () => {
       await listener.sanityCheck();
     });
   });
+
   describe('stream', () => {
     test('successful flow', async () => {
       const { fetch, handleRequest } = mockStreamingChatCompletionFetch();
@@ -2273,5 +2274,55 @@ describe('resource completions', () => {
       expect(listener.finalMessage).toEqual({ role: 'assistant', content: 'The weather is great today!' });
       await listener.sanityCheck();
     });
+    test('handles network errors', async () => {
+      const { fetch, handleRequest } = mockFetch();
+
+      const openai = new OpenAI({ apiKey: '...', fetch });
+
+      const stream = openai.beta.chat.completions.stream(
+        {
+          max_tokens: 1024,
+          model: 'gpt-3.5-turbo',
+          messages: [{ role: 'user', content: 'Say hello there!' }],
+        },
+        { maxRetries: 0 },
+      );
+
+      handleRequest(async () => {
+        throw new Error('mock request error');
+      }).catch(() => {});
+
+      async function runStream() {
+        await stream.done();
+      }
+
+      await expect(runStream).rejects.toThrow(APIConnectionError);
+    });
+    test('handles network errors on async iterator', async () => {
+      const { fetch, handleRequest } = mockFetch();
+
+      const openai = new OpenAI({ apiKey: '...', fetch });
+
+      const stream = openai.beta.chat.completions.stream(
+        {
+          max_tokens: 1024,
+          model: 'gpt-3.5-turbo',
+          messages: [{ role: 'user', content: 'Say hello there!' }],
+        },
+        { maxRetries: 0 },
+      );
+
+      handleRequest(async () => {
+        throw new Error('mock request error');
+      }).catch(() => {});
+
+      async function runStream() {
+        for await (const _event of stream) {
+          continue;
+        }
+      }
+
+      await expect(runStream).rejects.toThrow(APIConnectionError);
+    });
   });
 });

src/lib/ChatCompletionStream.ts

@@ -210,13 +210,16 @@ export class ChatCompletionStream
 
   [Symbol.asyncIterator](): AsyncIterator<ChatCompletionChunk> {
     const pushQueue: ChatCompletionChunk[] = [];
-    const readQueue: ((chunk: ChatCompletionChunk | undefined) => void)[] = [];
+    const readQueue: {
+      resolve: (chunk: ChatCompletionChunk | undefined) => void;
+      reject: (err: unknown) => void;
+    }[] = [];
     let done = false;
 
     this.on('chunk', (chunk) => {
       const reader = readQueue.shift();
       if (reader) {
-        reader(chunk);
+        reader.resolve(chunk);
       } else {
         pushQueue.push(chunk);
       }
@@ -225,7 +228,23 @@ export class ChatCompletionStream
     this.on('end', () => {
       done = true;
       for (const reader of readQueue) {
-        reader(undefined);
+        reader.resolve(undefined);
+      }
+      readQueue.length = 0;
+    });
+
+    this.on('abort', (err) => {
+      done = true;
+      for (const reader of readQueue) {
+        reader.reject(err);
+      }
+      readQueue.length = 0;
+    });
+
+    this.on('error', (err) => {
+      done = true;
+      for (const reader of readQueue) {
+        reader.reject(err);
       }
       readQueue.length = 0;
     });
@@ -236,13 +255,17 @@ export class ChatCompletionStream
           if (done) {
             return { value: undefined, done: true };
           }
-          return new Promise<ChatCompletionChunk | undefined>((resolve) => readQueue.push(resolve)).then(
-            (chunk) => (chunk ? { value: chunk, done: false } : { value: undefined, done: true }),
-          );
+          return new Promise<ChatCompletionChunk | undefined>((resolve, reject) =>
+            readQueue.push({ resolve, reject }),
+          ).then((chunk) => (chunk ? { value: chunk, done: false } : { value: undefined, done: true }));
         }
         const chunk = pushQueue.shift()!;
         return { value: chunk, done: false };
       },
+      return: async () => {
+        this.abort();
+        return { value: undefined, done: true };
+      },
     };
   }