[V4] Message formatting is incompatible with Webpack v5

Created by: femesq

TypeError: message.split is not a function

error occurs when webpack throws any error during compilation

Seems like this line should check if message is an object with and message key, as webpack v5 mentions in migration guide:

Stats json errors and warnings no longer contain strings but objects with information splitted into properties.
MIGRATION: Access the information on the properties. i. e. message

Environment

webpack: "5.2.0" react-dev-utils: "11.0.0"