feat: return streaming errors as an event formatted for openai's client (#2668)

* feat: return streaming errors as an event formatted for openai's client

* fix: propagate completions error events to stream

* fix: improve stream api error format and add status code

* fix: improve streamin error to include error_type

* Revert "fix: improve streamin error to include error_type"

This reverts commit 2b1a360b1511d94ea9a24e5432e498e67939506a.

* Reworked the implementation.

* Revert "Reworked the implementation."

This reverts commit 7c3f29777f17411ae4ade57e2f88e73cde704ee5.

* Small lifting.

---------
Co-authored-by: Nicolas Patry <patry.nicolas@protonmail.com>

router/src/infer/mod.rs

@@ -10,10 +10,12 @@ use crate::{
 };
 use async_stream::stream;
 use async_trait::async_trait;
+use axum::response::sse::Event;
 use chat_template::ChatTemplate;
 use futures::future::try_join_all;
 use futures::Stream;
 use minijinja::ErrorKind;
+use serde::Serialize;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 use thiserror::Error;
@@ -373,4 +375,26 @@ impl InferError {
             InferError::StreamSerializationError(_) => "stream_serialization_error",
         }
     }
+
+    pub(crate) fn into_openai_event(self) -> Event {
+        Event::default()
+            .json_data(OpenaiErrorEvent {
+                error: APIError {
+                    message: self.to_string(),
+                    http_status_code: 422,
+                },
+            })
+            .unwrap()
+    }
+}
+
+#[derive(Serialize)]
+pub struct APIError {
+    message: String,
+    http_status_code: usize,
+}
+
+#[derive(Serialize)]
+pub struct OpenaiErrorEvent {
+    error: APIError,
 }

router/src/server.rs

@@ -866,7 +866,7 @@ pub(crate) async fn completions(
 
                                     yield Ok(event);
                                 }
-                                Err(err) => yield Ok(Event::from(err)),
+                                Err(err) => yield Ok(err.into_openai_event()),
                             }
                         }
                     };
@@ -1274,7 +1274,8 @@ pub(crate) async fn chat_completions(
             };
             let mut response_as_tool = using_tools;
             while let Some(result) = response_stream.next().await {
-                if let Ok(stream_token) = result {
+                match result{
+                Ok(stream_token) => {
                     let token_text = &stream_token.token.text.clone();
                     match state {
                         StreamState::Buffering => {
@@ -1368,6 +1369,8 @@ pub(crate) async fn chat_completions(
                         }
                     }
                 }
+                Err(err) => yield Ok(err.into_openai_event())
+                }
             }
             yield Ok::<Event, Infallible>(Event::default().data("[DONE]"));
         };