process/stdio: fix ref watching for readable stream.

See: nodejs/node#28153

Author: chjj

lib/process/stdio.js

@@ -30,8 +30,11 @@ class Readable extends stream.Readable {
     this._started = false;
 
     this.on('end', () => {
-      if (this._increments && --this._port._stdioRefs === 0)
-        this._port._stdioRef.unref();
+      // See: https://github.com/nodejs/node/pull/28153
+      if (this._started && this._increments) {
+        if (--this._port._stdioRefs === 0)
+          this._port._stdioRef.unref();
+      }
     });
   }