fixup! fixup! debugger: fix event listener leak in the run command

Author: joyeecheung

lib/internal/debugger/inspect_client.js

@@ -13,7 +13,7 @@ const {
 const Buffer = require('buffer').Buffer;
 const crypto = require('crypto');
 const { ERR_DEBUGGER_ERROR } = require('internal/errors').codes;
-const { EventEmitter } = require('events');
+const { EventEmitter, once } = require('events');
 const http = require('http');
 const { URL } = require('internal/url');
 
@@ -343,25 +343,10 @@ class Client extends EventEmitter {
       this.emit('ready');
     };
 
-    return new Promise((resolve, reject) => {
-      const tearDown = () => {
-        this.removeListener('ready', onReady);
-        this.removeListener('error', onError);
-      };
-      const onError = (err) => {
-        tearDown();
-        reject(err);
-      };
-      const onReady = () => {
-        tearDown();
-        resolve();
-      };
-      this.on('error', onError);
-      this.on('ready', onReady);
-
-      httpReq.on('upgrade', handshakeListener);
-      httpReq.end();
-    });
+    const onReady = once(this, 'ready');
+    httpReq.on('upgrade', handshakeListener);
+    httpReq.end();
+    return onReady;
   }
 }