fix(cli): handle chat output errors (#10229)

Propagate terminal write errors from the chat prompt and explicitly ignore stream close errors during cleanup.

Update chat tests to assert response writer errors so errcheck passes without hiding failed writes.

Tests:
- go test -count=1 ./core/cli/chat
- go test -count=1 ./core/cli

Assisted-by: Codex:GPT-5

Signed-off-by: Ching Kao <0980124jim@gmail.com>

core/cli/chat/chat_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"strings"
@@ -19,7 +20,7 @@ var _ = Describe("Run chat", func() {
 		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			if r.URL.Path == "/v1/models" {
 				w.Header().Set("Content-Type", "application/json")
-				fmt.Fprint(w, `{"object":"list","data":[{"id":"test-model","object":"model"}]}`)
+				writeResponse(w, `{"object":"list","data":[{"id":"test-model","object":"model"}]}`)
 				return
 			}
 
@@ -40,9 +41,9 @@ var _ = Describe("Run chat", func() {
 			Expect(body.Messages[0].Content).To(Equal("hello"))
 
 			w.Header().Set("Content-Type", "text/event-stream")
-			fmt.Fprint(w, "data: {\"choices\":[{\"index\":0,\"delta\":{\"content\":\"hi\"}}]}\n\n")
-			fmt.Fprint(w, "data: {\"choices\":[{\"index\":0,\"delta\":{\"content\":\"!\"}}]}\n\n")
-			fmt.Fprint(w, "data: [DONE]\n\n")
+			writeResponse(w, "data: {\"choices\":[{\"index\":0,\"delta\":{\"content\":\"hi\"}}]}\n\n")
+			writeResponse(w, "data: {\"choices\":[{\"index\":0,\"delta\":{\"content\":\"!\"}}]}\n\n")
+			writeResponse(w, "data: [DONE]\n\n")
 		}))
 		defer server.Close()
 
@@ -135,14 +136,14 @@ func chatTestServer(models []string, onChat func(model string)) *httptest.Server
 		switch r.URL.Path {
 		case "/v1/models":
 			w.Header().Set("Content-Type", "application/json")
-			fmt.Fprint(w, `{"object":"list","data":[`)
+			writeResponse(w, `{"object":"list","data":[`)
 			for i, model := range models {
 				if i > 0 {
-					fmt.Fprint(w, ",")
+					writeResponse(w, ",")
 				}
-				fmt.Fprintf(w, `{"id":%q,"object":"model"}`, model)
+				writeResponsef(w, `{"id":%q,"object":"model"}`, model)
 			}
-			fmt.Fprint(w, `]}`)
+			writeResponse(w, `]}`)
 		case "/v1/chat/completions":
 			var body struct {
 				Model string `json:"model"`
@@ -152,10 +153,20 @@ func chatTestServer(models []string, onChat func(model string)) *httptest.Server
 				onChat(body.Model)
 			}
 			w.Header().Set("Content-Type", "text/event-stream")
-			fmt.Fprint(w, "data: {\"choices\":[{\"index\":0,\"delta\":{\"content\":\"ok\"}}]}\n\n")
-			fmt.Fprint(w, "data: [DONE]\n\n")
+			writeResponse(w, "data: {\"choices\":[{\"index\":0,\"delta\":{\"content\":\"ok\"}}]}\n\n")
+			writeResponse(w, "data: [DONE]\n\n")
 		default:
 			w.WriteHeader(http.StatusNotFound)
 		}
 	}))
 }
+
+func writeResponse(w io.Writer, text string) {
+	_, err := fmt.Fprint(w, text)
+	Expect(err).ToNot(HaveOccurred())
+}
+
+func writeResponsef(w io.Writer, format string, args ...any) {
+	_, err := fmt.Fprintf(w, format, args...)
+	Expect(err).ToNot(HaveOccurred())
+}

core/cli/chat/client.go

@@ -50,7 +50,9 @@ func (c *localAIChatClient) StreamChat(ctx context.Context, model string, messag
 	if err != nil {
 		return "", friendlyChatError(err, model)
 	}
-	defer stream.Close()
+	defer func() {
+		_ = stream.Close()
+	}()
 
 	var answer strings.Builder
 	for {

core/cli/chat/terminal.go

@@ -12,11 +12,17 @@ func runTerminalChat(ctx context.Context, session *chatSession, in io.Reader, ou
 	scanner := bufio.NewScanner(in)
 	scanner.Buffer(make([]byte, 0, 64*1024), 4*1024*1024)
 
-	fmt.Fprintf(out, "LocalAI chat (%s)\n", session.CurrentModel())
-	fmt.Fprintln(out, "Type /exit to quit, /clear to reset the conversation, /models to list models.")
+	if err := writeChat(out, "LocalAI chat (%s)\n", session.CurrentModel()); err != nil {
+		return err
+	}
+	if err := writeChat(out, "Type /exit to quit, /clear to reset the conversation, /models to list models.\n"); err != nil {
+		return err
+	}
 
 	for {
-		fmt.Fprint(out, "\n> ")
+		if err := writeChat(out, "\n> "); err != nil {
+			return err
+		}
 		if !scanner.Scan() {
 			break
 		}
@@ -26,45 +32,62 @@ func runTerminalChat(ctx context.Context, session *chatSession, in io.Reader, ou
 		case "":
 			continue
 		case "/bye", "/exit", "/quit":
-			fmt.Fprintln(out, "bye")
-			return nil
+			return writeChat(out, "bye\n")
 		case "/clear":
 			session.Clear()
-			fmt.Fprintln(out, "conversation cleared")
+			if err := writeChat(out, "conversation cleared\n"); err != nil {
+				return err
+			}
 			continue
 		case "/models":
-			printChatModels(out, session.Models(), session.CurrentModel())
+			if err := printChatModels(out, session.Models(), session.CurrentModel()); err != nil {
+				return err
+			}
 			continue
 		}
 
 		if nextModel, ok := strings.CutPrefix(prompt, "/model "); ok {
 			nextModel = strings.TrimSpace(nextModel)
 			if nextModel == "" {
-				fmt.Fprintln(out, "usage: /model <name>")
+				if err := writeChat(out, "usage: /model <name>\n"); err != nil {
+					return err
+				}
 				continue
 			}
 			if err := session.SwitchModel(nextModel); err != nil {
-				fmt.Fprintln(out, err)
+				if writeErr := writeChat(out, "%s\n", err); writeErr != nil {
+					return writeErr
+				}
 				continue
 			}
-			fmt.Fprintf(out, "switched to %s; conversation cleared\n", session.CurrentModel())
+			if err := writeChat(out, "switched to %s; conversation cleared\n", session.CurrentModel()); err != nil {
+				return err
+			}
 			continue
 		}
 
-		fmt.Fprint(out, "assistant: ")
+		if err := writeChat(out, "assistant: "); err != nil {
+			return err
+		}
 		if err := session.Send(ctx, prompt, out); err != nil {
 			return err
 		}
-		fmt.Fprintln(out)
+		if err := writeChat(out, "\n"); err != nil {
+			return err
+		}
 	}
 
 	return scanner.Err()
 }
 
-func printChatModels(out io.Writer, models []string, current string) {
+func printChatModels(out io.Writer, models []string, current string) error {
 	if len(models) == 0 {
-		fmt.Fprintln(out, "no models installed")
-		return
+		return writeChat(out, "no models installed\n")
 	}
-	fmt.Fprint(out, formatChatModelList(models, current))
+	return writeChat(out, "%s", formatChatModelList(models, current))
+}
+
+func writeChat(out io.Writer, format string, args ...any) error {
+	_, err := fmt.Fprintf(out, format, args...)
+	return err
 }