message: Add comment about Webpack plugin to fail builds on warnings
diff: * limitations under the License.
  */
  +/**
  + * When building storybook, we can have warnings which may cause issues in the future. One of the example case is
  + * https://github.com/spotify/backstage/issues/718. To make sure new warnings are not introduced with new PRs, we
  + * want to fail CI builds if there are warnings when building storybook.
  + *
  + * This webpack plugin makes sure the CI builds fail on Webpack warnings. We also have a whitelist of warnings here
  + * which we think are non-critical.
  + *
  + * Note that this implementation will not detect other warnings emitted by storybook build that are separate from
  + * Webpack. A better solution over this plugin should be preferred, possibly on Storybook level (CLI options etc.)
  + *
  + * The case with #718 is caused because we are using `ts-loader` for `webpack` to load all our JS/TS files, but we
  + * have disabled type checking during build. This is done by setting `transpileOnly` to `true` in storybook/main.js
  + * and it improves the Storybook build speed. Because of this, Webpack emits warnings when we try to re-export types.
  + * Reference: https://github.com/TypeStrong/ts-loader#transpileonly
  + */
  class WebpackPluginFailBuildOnWarning {
  // Ignore the following warnings in the Webpack build.
  warningsWhitelist = new Set([
  