fix: prevent new workers from writing to closed pool

src/entry/process.ts

@@ -43,7 +43,7 @@ process.on('message', (message: IncomingMessage) => {
         ready: true,
         source: 'pool',
         __tinypool_worker_message__: true,
-      })
+      }) // TODO: Add no-op
     })().catch(throwInNextTick)
 
     return

test/fixtures/nested-pool.mjs

@@ -0,0 +1,17 @@
+import { cpus } from 'os'
+import { Tinypool } from 'tinypool'
+
+export default async function nestedPool() {
+  const pool = new Tinypool({
+    filename: new URL(import.meta.url, import.meta.url).href,
+    runtime: 'child_process',
+    isolateWorkers: true,
+    minThreads: cpus().length - 1,
+    maxThreads: cpus().length - 1,
+  })
+
+  await Promise.resolve()
+  pool.recycleWorkers()
+}
+
+export function entrypoint() {}

test/termination.test.ts

@@ -56,3 +56,21 @@ test('writing to terminating worker does not crash', async () => {
 
   await destroyed
 })
+
+test('recycling workers while closing pool does not crash', async () => {
+  const pool = new Tinypool({
+    runtime: 'child_process',
+    filename: resolve(__dirname, 'fixtures/nested-pool.mjs'),
+    isolateWorkers: true,
+    minThreads: 1,
+    maxThreads: 1,
+  })
+
+  await Promise.all(
+    Array(50)
+      .fill(() => pool.run({}))
+      .map((fn) => fn())
+  )
+
+  await pool.destroy()
+})