Disable error overlay in development mode

An alternate solution is to add the following CSS style:

iframe
{
    display: none;
}

This prevents the error from showing.

We don't provide an option to disable the error overlay in development. Error boundaries do not take its place (they are meant for production use).

There is no harm having both the development error overlay and your error boundary; simply press Escape if you'd like to view your error boundary.

We feel the error overlay provides tremendous value over your typical error boundary (source code, click to open, etc). It is also vital as we explore enabling hot component reloading as a default behavior for all users.

If you feel strongly about disabling the overlay, you'll need to eject from react-scripts and discontinue use of webpackHotDevClient. A less intrusive method may be removing the error event listener installed by the overlay off of window.