message: remove if branch for findBuilder
diff: @@ -156,12 +156,10 @@ const findConfigFlags = async ({ options, packageJson }) => {
  };
  export const findBuilder = async (mainConfig) => {
  - let name: string;
  + let name = 'webpack4'; // default builder in Storybook v6
  if (mainConfig?.core.builder) {
  const { builder } = mainConfig.core;
  name = typeof builder === 'string' ? builder : builder.name;
  - } else {
  - name = 'webpack4';
  }
  return Promise.race([
  