message: build: introduce a temporary patch to make node_modules/rxjs compile with typescript 2.7
  This patch can be removed once we update to rxjs v6. See
  PR Close
diff: @@ -9,5 +9,11 @@ set('-v');
  // jump to project root
  cd(path.join(__dirname, '../'));
  +// https://github.com/ReactiveX/rxjs/pull/3302
  +// make node_modules/rxjs compilable with Typescript 2.7
  +// remove when we update to rxjs v6
  +console.log('\n# patch: reactivex/rxjs#3302 make node_modules/rxjs compilable with Typescript 2.7')
  +sed('-i', "('response' in xhr)", "('response' in (xhr as any))", "node_modules/rxjs/src/observable/dom/AjaxObservable.ts")
  +
  console.log('===== finished running the postinstall.js script =====');
  