Add BAD_REQUEST status code

source/constants.ts

@@ -13,6 +13,11 @@ export const HTTP_STATUS_CODE_CREATED = 201;
  */
 export const HTTP_STATUS_CODE_NO_CONTENT = 204;
 
+/**
+ * Bad request response status code.
+ */
+export const HTTP_STATUS_CODE_BAD_REQUEST = 400;
+
 /**
  * HTTP status code for "Not Acceptable" error.
  */

source/services/transport/http-transport.ts

@@ -3,13 +3,15 @@ import { streamSSE } from 'hono/streaming';
 import { toExtendedJson, fromExtendedJson } from '@xo-cash/utils';
 
 import type { Logger } from '../../utils/logger.ts';
-import { ApplicationError, normalizePublicError } from '../../errors/index.ts';
 import type { ApplicationRequest, ApplicationRouter } from '../router.ts';
-import { HonoSSEStream } from '../stream/hono-sse-stream.ts';
-import { HttpRequestStream } from '../stream/http-request-stream.ts';
 import type { StreamResponse } from '../stream/base-stream.ts';
 import type { AppEnv, TransportRouter } from './transport-router.ts';
 
+import { ApplicationError, normalizePublicError } from '../../errors/index.ts';
+import { HTTP_STATUS_CODE_BAD_REQUEST, HTTP_STATUS_CODE_NO_CONTENT } from '../../constants.ts';
+import { HonoSSEStream } from '../stream/hono-sse-stream.ts';
+import { HttpRequestStream } from '../stream/http-request-stream.ts';
+
 /** Hono context key where decoded Extended JSON bodies are stored. */
 const PARSED_BODY_KEY = 'parsedBody';
 
@@ -90,7 +92,7 @@ export class HttpTransportRouter implements TransportRouter {
                     c.set(PARSED_BODY_KEY, parsed);
                 } catch (error) {
                     debug('invalid Extended JSON request: %O', error);
-                    throw new ApplicationError(400, 'Invalid JSON in request body');
+                    throw new ApplicationError(HTTP_STATUS_CODE_BAD_REQUEST, 'Invalid JSON in request body');
                 }
             }
 
@@ -209,8 +211,8 @@ export class HttpTransportRouter implements TransportRouter {
      * @param response - Buffered response from HttpRequestStream, if any.
      */
     private static toResponse(response: StreamResponse | undefined): Response {
-        if (!response || response.statusCode === 204) {
+        if (!response || response.statusCode === HTTP_STATUS_CODE_NO_CONTENT) {
-            return new Response(null, { status: 204 });
+            return new Response(null, { status: HTTP_STATUS_CODE_NO_CONTENT });
         }
 
         return new Response(toExtendedJson(response.body), {