Created by: daviesgeek
Pretty straightforward: mini-css-extract-plugin was updated to 2.5.0 6 hours ago.
The reason for this change is explained in more detail here: https://github.com/webpack-contrib/mini-css-extract-plugin/issues/896
This can break if you're not using yarn or some other way of pinning downstream dependencies.
Updated package.json to reflect version change. IMO this really should be a tilde ~ instead of a caret ^ to avoid issues like this in the future.