code: function defaultError(view, location) {
  	const code = (/^[45]\d\d$/).test(location.name) ? +location.name : 0;
  	view.document.body['inner'+'HTML'] = `<h1 id="code"></h1><span id="message"></span>`
  	+`<style> :root { background: #424F5A; filter: invert(1) hue-rotate(180deg); font-family: Segoe UI, Tahoma, sans-serif; } </style>`;
  	view.document.querySelector('#message').textContent = code ? view.history.state && view.history.state.message || '' : `Unknown view "${ location.name }"`;
  	view.document.querySelector('#code').textContent = code || 404;
  	view.document.title = !code || code === 404 ? 'Not Found' : view.history.state && view.history.state.title || 'Error';
  	!code && console.error(`Got unknown view "${ view.location.hash.slice(1) }"`);
  	location.onChange(() => view.location.reload());
  }
docs: default error handler