stream: propagate destruction in duplexPair

Ensure destroying one side of a duplexPair triggers destruction of the
other side via process.nextTick(). Only the destruction signal is sent
to avoid breaking changes.

Fixes: #61015

Author: aelhor

lib/internal/streams/duplexpair.js

@@ -50,13 +50,37 @@ class DuplexSide extends Duplex {
     this.#otherSide.on('end', callback);
     this.#otherSide.push(null);
   }
+
+
+  _destroy(err, callback) {
+    const otherSide = this.#otherSide;
+
+    if (otherSide !== null && !otherSide.destroyed) {
+      // Use nextTick to avoid crashing the current execution stack (like HTTP parser)
+      process.nextTick(() => {
+        if (otherSide.destroyed) return;
+
+        if (err) {
+          // Destroy the other side, without passing the 'err' object.
+          // This closes the other side gracefully so it doesn't hang,
+          // but prevents the "Unhandled error" crash.
+          otherSide.destroy();
+        } else {
+          // Standard graceful close
+          otherSide.push(null);
+        }
+      });
+    }
+
+    callback(err);
+  }
 }
 
 function duplexPair(options) {
   const side0 = new DuplexSide(options);
   const side1 = new DuplexSide(options);
   side0[kInitOtherSide](side1);
   side1[kInitOtherSide](side0);
-  return [ side0, side1 ];
+  return [side0, side1];
 }
 module.exports = duplexPair;

test/parallel/test-duplex-error.js

@@ -0,0 +1,32 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const { duplexPair } = require('stream');
+
+const [sideA, sideB] = duplexPair();
+
+// Side A should receive the error because we called .destroy(err) on it.
+sideA.on('error', common.mustCall((err) => {
+  assert.strictEqual(err.message, 'Simulated error');
+}));
+
+// Side B should NOT necessarily emit an error (to avoid crashing
+// existing code), but it MUST be destroyed.
+sideB.on('error', common.mustNotCall('Side B should not emit an error event'));
+
+sideB.on('close', common.mustCall(() => {
+  assert.strictEqual(sideB.destroyed, true);
+}));
+
+sideA.resume();
+sideB.resume();
+
+// Trigger the destruction
+sideA.destroy(new Error('Simulated error'));
+
+// Check the state in the next tick to allow nextTick/microtasks to run
+setImmediate(common.mustCall(() => {
+  assert.strictEqual(sideA.destroyed, true);
+  assert.strictEqual(sideB.destroyed, true);
+}));