Crosswalk + Ionic4

crosswalk

//star blank Ionic project
ionic start walk sidemenu --type=angular

//change to Ionic project folder
cd walk

//add android platform
ionic cordova platform add android

//remove Ionic webview
ionic cordova plugin remove cordova-plugin-ionic-webview

//add crosswalk webview
ionic cordova plugin add cordova-plugin-crosswalk-webview

//add plugin to fix crosswalk build error due to gradle error
ionic cordova plugin add cordova-android-support-gradle-release

//modify src/index.html and change 
 <base href="/" />
//to
 <base href="/android_asset/www/" />

//modify src/main.ts to fix "URL scheme "file" is not supported." when loading SVG assets
//https://github.com/ionic-team/ionicons/issues/572#issuecomment-402895894
//add

function androidFetchWorkaround() {
  const originalFetch = (window as any).fetch;

  (window as any).fetch = (...args) => {
    const [url] = args;

    if (typeof url === 'string' && url.match(/\.svg/)) {
      return new Promise((resolve, reject) => {
        const req = new XMLHttpRequest();
        req.open('GET', url, true);
        req.addEventListener('load', () => {
          resolve({ ok: true, text: () => Promise.resolve(req.responseText) });
        });
        req.addEventListener('error', reject);
        req.send();
      });
    } else {
      return originalFetch(...args);
    }
  };
}

androidFetchWorkaround();

//above

platformBrowserDynamic().bootstrapModule(AppModule)
  .catch(err => console.log(err));

//run on android
ionic cordova run android

I'm getting
Failed to load resource: net::ERR_FILE_NOT_FOUND
with both <base href="/android_asset/www/" /> and <base href="/" />