fix: handle HTTP 304 response status code

In case 304 is returned, the cached version of the result should be used, so consider this response as success. NOTE: It can be returned only when specific header is sent in the request, so the caller actually expects to receive either 304 or 200 with new content.

Author: rosen-vladimirov

lib/common/constants.ts

@@ -92,6 +92,7 @@ export class Proxy {
  */
 export class HttpStatusCodes {
 	static SEE_OTHER = 303;
+	static NOT_MODIFIED = 304;
 	static PAYMENT_REQUIRED = 402;
 	static PROXY_AUTHENTICATION_REQUIRED = 407;
 }

lib/common/http-client.ts

@@ -168,7 +168,7 @@ export class HttpClient implements Server.IHttpClient {
 							this.setResponseResult(promiseActions, cleanupRequestData, { err: new Error(HttpClient.STUCK_RESPONSE_ERROR_MESSAGE) });
 						}
 					}, HttpClient.STUCK_RESPONSE_CHECK_INTERVAL);
-					const successful = helpers.isRequestSuccessful(responseData);
+					const successful = helpers.isRequestSuccessful(responseData) || responseData.statusCode === HttpStatusCodes.NOT_MODIFIED;
 					if (!successful) {
 						pipeTo = undefined;
 					}