Use of single-spa-layout causes twice loaded warning.

[barryspearce]

I have two copies of my shell application. The first uses an MFE List and registers the apps:

const mfeList: any = [
    {
        name: 'widget1',
        app: () => import('widget1'),
        activeWhen: '/',
    },
        {
        name: 'widget2',
        app: () => import('widget2'),
        activeWhen: '/'
    },
    {
        name: 'nav',
        app: () => import('nav'),
        activeWhen: '/',
    },
    {
        name: 'app1',
        app: () => import('app1'),
        activeWhen: '/app1',
    },
    {
        name: 'app2',
        app: () => import('app2'),
        activeWhen: '/app2',
    },
    {
        name: 'app3',
        app: () => import('app3'),
        activeWhen: '/app3',
    },
    {
        name: 'footer',
        app: () => import('footer'),
        activeWhen: '/',
    }
]
mfeList.map((mfe: any) => registerApplication({
    ...mfe,
    customProps: {
        publish,
        subscribe,
        comms,
        config
    }
}));

start();

This works without warning. However, moving this over into spa-single-layout causes the warning that single-spa has been loaded twice on the page, and this causes single-spa-inspector to stop working:

export const mfeLayout = `
<single-spa-router mode="history" base="/" containerEl="#main-router">
    <nav class="topnav">
        <application name="nav" props="publish,subscribe,comms,config"></application>
    </nav>
    <div class="main-content">
        <route path="/app1">
            <application name="app1" props="publish,subscribe,comms,config"></application>
        </route>
        <route path="/app2">
            <application name="app2" props="publish,subscribe,comms,config"></application>
        </route>
        <route path="/app3">
            <application name="app3" props="publish,subscribe,comms,config"></application>
        </route>
        <route default>
            <h1>404 Not Found</h1>
        </route>
    </div>
    <footer>
        <application name="footer" props="publish,subscribe,comms,config"></application>
    </footer>
</single-spa-router>
`;
// Layout MFEs.
const routes = constructRoutes(mfeLayout, { props: appInfrastructure });
const applications = constructApplications({
    routes,
    loadApp({ name }) {
        return import(name)
    },
});
const layoutEngine = constructLayoutEngine({ routes, applications });
applications.forEach(registerApplication);

start();