add init of cancelMap

Author: Stefan Schubert

src/mustache/api.service.mustache

@@ -67,7 +67,7 @@ export class {{classname}} {
     protected basePath = '{{{basePath}}}';
     public defaultHeaders = new {{#useHttpClient}}Http{{/useHttpClient}}Headers();
     public configuration = new Configuration();
-    private cancelMap: {[key: string]: Subject<any>};
+    private cancelMap: {[key: string]: Subject<any>} = {};
 
     constructor(protected {{#useHttpClient}}httpClient: HttpClient{{/useHttpClient}}{{^useHttpClient}}http: Http{{/useHttpClient}}, @Optional()@Inject(BASE_PATH) basePath: string, @Optional() configuration: Configuration) {