feat: stub cluster module in bundles

bundler/bundle.js

@@ -174,6 +174,7 @@ export const build = async (...files) => {
     buffer: hasBuffer ? api('node-buffer.cjs') : dirname(resolveRequire('buffer/')),
     child_process: api('child_process.cjs'),
     constants: resolveRequire('constants-browserify'),
+    cluster: api('cluster.cjs'),
     crypto: api('crypto.cjs'),
     events: dirname(resolveRequire('events/')),
     fs: api('fs.cjs'),

bundler/modules/cluster.cjs

@@ -0,0 +1,27 @@
+const EventEmitter = require('events')
+
+const makeMethod = (key) => {
+  // Not an arrow as Worker is a class and can be called with new
+  return function () {
+    throw new Error(`cluster.${key} unsupported in bundled mode`)
+  }
+}
+
+const cluster = new EventEmitter()
+
+Object.assign(cluster, {
+  isWorker: false,
+  isPrimary: true,
+  workers: {},
+  settings: {},
+  SCHED_NONE: 1,
+  SCHED_RR: 2,
+  schedulingPolicy: 2,
+})
+
+for (const key of ['Worker', 'setupPrimary', 'fork', 'disconnect']) cluster[key] = makeMethod(key)
+
+cluster.isMaster = cluster.isPrimary
+cluster.setupMaster = cluster.setupPrimary
+
+module.exports = cluster

package.json

@@ -47,6 +47,7 @@
     "bundler/modules/ansi-styles.cjs",
     "bundler/modules/assert-strict.cjs",
     "bundler/modules/child_process.cjs",
+    "bundler/modules/cluster.cjs",
     "bundler/modules/crypto.cjs",
     "bundler/modules/fs.cjs",
     "bundler/modules/fs-promises.cjs",