webpack4を使用していたプロジェクトをwebpack5にアップデートした際に詰んだことまとめとく

ERROR in ./node_modules/i18next/node_modules/@babel/runtime/helpers/esm/inherits.js 1:0-46
Module not found: Error: Can't resolve './setPrototypeOf' in '/app/node_modules/i18next/node_modules/@babel/runtime/helpers/esm'
Did you mean 'setPrototypeOf.js'?
BREAKING CHANGE: The request './setPrototypeOf' failed to resolve only because it was resolved as fully specified
(probably because the origin is strict EcmaScript Module, e. g. a module with javascript mimetype, a '*.mjs' file, or a '*.js' file where the package.json contains '"type": "module"').
The extension in the request is mandatory for it to be fully specified.
Add the extension to the request.

{
  test: /\.m?js/,
  resolve: {
    fullySpecified: false
  }
}