not found crashes iOS app on load (sourcemap not found)

I have a create-react-app wrapped in Cordova, and I added sentry-cordova as per documentation.

I have the following in my index.js, in the ‘deviceready’ event handler:

    window.Sentry = window.cordova.require('sentry-cordova.Sentry');
      dsn: '', // [redacted]
    window.Sentry.captureMessage('initializing sentry');

    function failingFunction() {
      throw new Error('Sentry Test');

    window.sentry.addBreadcrumb({ message: 'initSentry' });
    try {
    } catch (e) {

When I run $ cordova run ios --target=iPad-Air-2 the app freezes as soon as it starts up, and all I get from the connected Safari Web Inspector is the following error:

Failed to load resource: The requested URL was not found on this server.

I found several posts with a fix for ionic apps, but nothing for a classic JS wrapped app.

If I comment out the lines starting from window.Sentry.captureMessage... to the end of the above snippet, the app works, so Sentry seems really the culprit.

Using sentry-cordova 0.13.1 and cordova 8.1.2