runBeforeMainModule is an empty array #78

const options = {
      assetExts: defaultAssetExts.concat(assetExts),
      assetRegistryPath: ASSET_REGISTRY_PATH,
      blacklistRE: config.getBlacklistRE(),
      extraNodeModules: config.extraNodeModules,
      getPolyfills: config.getPolyfills,
      getTransformOptions: config.getTransformOptions,
      globalTransformCache: null,
      hasteImpl: config.hasteImpl,
      maxWorkers: args.maxWorkers,
      platforms: defaultPlatforms.concat(platforms),
      postMinifyProcess: config.postMinifyProcess,
      postProcessModules: config.postProcessModules,
      postProcessBundleSourcemap: config.postProcessBundleSourcemap,
      projectRoots: config.getProjectRoots(),
      providesModuleNodeModules: providesModuleNodeModules,
      resetCache: args.resetCache,
      reporter: new TerminalReporter(terminal),
      runBeforeMainModule: config.runBeforeMainModule,
      sourceExts: defaultSourceExts.concat(sourceExts),
      transformCache: TransformCaching.useTempDir(),
      transformModulePath: transformModulePath,
      useDeltaBundler: false,
      watch: false,
      workerPath: config.getWorkerPath && config.getWorkerPath(),
};

packagerInstance = new Server(options);

// shared/output/bundle.js
function buildBundle(packagerClient: Server, requestOptions: RequestOptions) {
  return packagerClient.buildBundle({
    ...Server.DEFAULT_BUNDLE_OPTIONS,
    ...requestOptions,
    isolateModuleIDs: true,
  });
}

async buildBundle(options: BundleOptions): Promise<Bundle> {
    const bundle = await this._bundler.bundle(options);
    const modules = bundle.getModules();
    const nonVirtual = modules.filter(m => !m.virtual);
    bundleDeps.set(bundle, {
      files: new Map(
        nonVirtual.map(({sourcePath, meta}) => [
          sourcePath,
          meta != null ? meta.dependencies : [],
        ]),
      ),
      idToIndex: new Map(modules.map(({id}, i) => [id, i])),
      dependencyPairs: new Map(
        nonVirtual
          .filter(({meta}) => meta && meta.dependencyPairs)
          .map(m => [m.sourcePath, m.meta.dependencyPairs]),
      ),
      outdated: new Set(),
    });
    return bundle;
  }