fix build

Author: Delta456

javascript/node/selenium-webdriver/firefox.js

@@ -121,7 +121,6 @@ const zip = require('./io/zip')
 const { Browser, Capabilities, Capability } = require('./lib/capabilities')
 const { Zip } = require('./io/zip')
 const { getBinaryPaths } = require('./common/driverFinder')
-const portprober = require('./net/portprober')
 const FIREFOX_CAPABILITY_KEY = 'moz:firefoxOptions'
 
 /**
@@ -493,10 +492,6 @@ class ServiceBuilder extends remote.DriverService.Builder {
    */
   constructor(opt_exe) {
     super(opt_exe)
-    if (!this.args.includes('--connect-existing')) {
-      this.args.append('--websocket-port')
-      this.args.append(`${portprober.findFreePort()}`)
-    }
     this.setLoopback(true) // Required.
   }
 

javascript/node/selenium-webdriver/index.js

@@ -44,6 +44,7 @@ const BrowsingContext = require('./bidi/browsingContext')
 const BrowsingContextInspector = require('./bidi/browsingContextInspector')
 const ScriptManager = require('./bidi/scriptManager')
 const NetworkInspector = require('./bidi/networkInspector')
+const portprober = require('./net/portprober')
 const version = require('./package.json').version
 
 const Browser = capabilities.Browser
@@ -676,9 +677,15 @@ class Builder {
 
       case Browser.FIREFOX: {
         let service = null
+        // Allocate a free port for the websocket only when not connecting to an existing instance
+        // This avoids conflicts when multiple Firefox instances have started
         if (this.firefoxService_) {
           service = this.firefoxService_.build()
         }
+        if (!service?.args.includes('--connect-existing')) {
+          service?.args.append('--websocket-port')
+          service?.args.append(`${portprober.findFreePort()}`)
+        }
         return createDriver(firefox.Driver, capabilities, service)
       }