feat: Implement centralized error handling for chat completions route

Author: ericc-ch

src/routes/chat-completions/route.ts

@@ -1,5 +1,8 @@
+import type { BlankEnv, BlankInput } from "hono/types"
+import type { ContentfulStatusCode } from "hono/utils/http-status"
+
 import consola from "consola"
-import { Hono } from "hono"
+import { Hono, type Context } from "hono"
 import { FetchError } from "ofetch"
 
 import { handlerStreaming } from "./handler"
@@ -10,17 +13,89 @@ completionRoutes.post("/", async (c) => {
   try {
     return await handlerStreaming(c)
   } catch (error) {
-    if (error instanceof FetchError) {
-      consola.error(`Request failed: ${error.message}`, error.response?._data)
-    }
-    if (error instanceof Response) {
-      consola.error(
-        `Request failed: ${error.status} ${error.statusText}: ${await error.text()}`,
-      )
-    } else if (error instanceof Error) {
-      consola.error("Error:", error.message)
-    } else {
-      consola.error("Error:", error)
-    }
+    consola.error("Error occurred:", error)
+    return handleError(c, error)
   }
 })
+
+// Handle different error types with specific handlers
+async function handleError(
+  c: Context<BlankEnv, "/", BlankInput>,
+  error: unknown,
+) {
+  if (error instanceof FetchError) {
+    return handleFetchError(c, error)
+  }
+
+  if (error instanceof Response) {
+    return await handleResponseError(c, error)
+  }
+
+  if (error instanceof Error) {
+    return handleGenericError(c, error)
+  }
+
+  // Fallback for unknown error types
+  return c.json(
+    {
+      error: {
+        message: "An unknown error occurred",
+        type: "unknown_error",
+      },
+    },
+    500,
+  )
+}
+
+function handleFetchError(
+  c: Context<BlankEnv, "/", BlankInput>,
+  error: FetchError,
+) {
+  return c.json(
+    {
+      error: {
+        message: error.message,
+        type: "fetch_error",
+        data: error.response?._data as unknown,
+      },
+    },
+    (error.response?.status ?? 500) as ContentfulStatusCode,
+  )
+}
+
+async function handleResponseError(
+  c: Context<BlankEnv, "/", BlankInput>,
+  error: Response,
+) {
+  const errorText = await error.text()
+  consola.error(
+    `Request failed: ${error.status} ${error.statusText}: ${errorText}`,
+  )
+
+  return c.json(
+    {
+      error: {
+        message: error.statusText || "Request failed",
+        type: "response_error",
+        status: error.status,
+        details: errorText,
+      },
+    },
+    error.status as ContentfulStatusCode,
+  )
+}
+
+function handleGenericError(
+  c: Context<BlankEnv, "/", BlankInput>,
+  error: Error,
+) {
+  return c.json(
+    {
+      error: {
+        message: error.message,
+        type: "error",
+      },
+    },
+    500,
+  )
+}