Support ErrorResponse for error cases in all specified messages

Return the ErrorResponse message in the getStatusMessage() of
TspClientResponse.

Contributes to fix issue:

eclipse-cdt-cloud/trace-server-protocol#122

Signed-off-by: Bernd Hufmann <bernd.hufmann@ericsson.com>

Author: bhufmann

tsp-typescript-client/src/models/error-response.ts

@@ -0,0 +1,9 @@
+/**
+ * Model of an error response
+ */
+export interface ErrorResponse {
+    /**
+     * Trace's unique identifier
+     */
+    message: string;
+}

tsp-typescript-client/src/protocol/rest-client.ts

@@ -2,6 +2,7 @@ import fetch, { Headers } from 'node-fetch';
 import { Deserialized, Normalizer } from './serialization';
 import { TspClientResponse } from './tsp-client-response';
 import JSONBigConfig = require('json-bigint');
+import { ErrorResponse } from '../models/error-response';
 
 const JSONBig = JSONBigConfig({
     useNativeBigInt: true,
@@ -125,6 +126,12 @@ export class RestClient {
         if (response.headers?.get('Content-Type') === 'application/json') {
             try {
                 const parsed = this.jsonParse(response.text);
+
+                // Check if the server sent an error
+                if (response.status >= 400) {
+                     const message = (parsed as ErrorResponse).message || 'Unknown error';
+                     return new TspClientResponse(response.text, response.status, message);
+                }
                 try {
                     const responseModel = normalizer ? normalizer(parsed) : parsed;
                     return new TspClientResponse(response.text, response.status, response.statusText, responseModel);