[8.x] OpenAI: Ignore chunks with an empty `choices` list (#…

…192951) (#192960)

# Backport

This will backport the following commits from `main` to `8.x`:
- [OpenAI: Ignore chunks with an empty `choices` list
(#192951)](#192951)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

<!--BACKPORT [{"author":{"name":"Pierre
Gayvallet","email":"pierre.gayvallet@elastic.co"},"sourceCommit":{"committedDate":"2024-09-15T18:28:44Z","message":"OpenAI:
Ignore chunks with an empty `choices` list (#192951)\n\n##
Summary\r\n\r\nOpenAI added usage stats to their APIs
recently:\r\nhttps://community.openai.com/t/usage-stats-now-available-when-using-streaming-with-the-chat-completions-api-or-completions-api/738156\r\n\r\nHowever,
it's somewhat non BWC:\r\n\r\n> Note that this usage-specific chunk will
have choices: [], so if you\r\nturn this feature on, you may need to
update any code that accesses\r\n\r\n(Héhéhé)\r\n\r\nLeveraging this
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thing to
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Ignore chunks with an empty `choices` list (#192951)\n\n##
Summary\r\n\r\nOpenAI added usage stats to their APIs
recently:\r\nhttps://community.openai.com/t/usage-stats-now-available-when-using-streaming-with-the-chat-completions-api-or-completions-api/738156\r\n\r\nHowever,
it's somewhat non BWC:\r\n\r\n> Note that this usage-specific chunk will
have choices: [], so if you\r\nturn this feature on, you may need to
update any code that accesses\r\n\r\n(Héhéhé)\r\n\r\nLeveraging this
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Ignore chunks with an empty `choices` list (#192951)\n\n##
Summary\r\n\r\nOpenAI added usage stats to their APIs
recently:\r\nhttps://community.openai.com/t/usage-stats-now-available-when-using-streaming-with-the-chat-completions-api-or-completions-api/738156\r\n\r\nHowever,
it's somewhat non BWC:\r\n\r\n> Note that this usage-specific chunk will
have choices: [], so if you\r\nturn this feature on, you may need to
update any code that accesses\r\n\r\n(Héhéhé)\r\n\r\nLeveraging this
feature is for another day. This PR is just about\r\navoiding the whole
thing to
explode.","sha":"8bffd618059aacc30d6190a0d143d8b0c7217faf"}},{"branch":"8.x","label":"v8.16.0","branchLabelMappingKey":"^v8.16.0$","isSourceBranch":false,"state":"NOT_CREATED"}]}]
BACKPORT-->

Co-authored-by: Pierre Gayvallet <pierre.gayvallet@elastic.co>

x-pack/plugins/actions/server/lib/get_token_count_from_openai_stream.ts

@@ -90,7 +90,9 @@ export async function getTokenCountFromOpenAIStream({
           delta: { content?: string; function_call?: { name?: string; arguments: string } };
         }>;
       } => {
-        return 'object' in line && line.object === 'chat.completion.chunk';
+        return (
+          'object' in line && line.object === 'chat.completion.chunk' && line.choices.length > 0
+        );
       }
     )
     .reduce(

x-pack/plugins/inference/server/chat_complete/adapters/openai/openai_adapter.ts

@@ -74,7 +74,7 @@ export const openAIAdapter: InferenceConnectorAdapter = {
       }),
       filter(
         (line): line is OpenAI.ChatCompletionChunk =>
-          'object' in line && line.object === 'chat.completion.chunk'
+          'object' in line && line.object === 'chat.completion.chunk' && line.choices.length > 0
       ),
       map((chunk): ChatCompletionChunkEvent => {
         const delta = chunk.choices[0].delta;

x-pack/plugins/observability_solution/observability_ai_assistant/server/service/client/adapters/process_openai_stream.ts

@@ -98,7 +98,7 @@ export function processOpenAiStream({
         }),
         filter(
           (line): line is CreateChatCompletionResponseChunk =>
-            'object' in line && line.object === 'chat.completion.chunk'
+            'object' in line && line.object === 'chat.completion.chunk' && line.choices.length > 0
         ),
         map((chunk): ChatCompletionChunkEvent => {
           const delta = chunk.choices[0].delta;