fix: fixes "url" argument must be of type string with nodejs 20

node:internal/errors:541
      throw error;
      ^

TypeError [ERR_INVALID_ARG_TYPE]: The "url" argument must be of type string. Received undefined
    at Url.parse (node:url:170:3)
    at Object.urlParse [as parse] (node:url:141:13)
    at new FtpServer (C:\work\xemu\xemu-bsp-list\ftp-srv\src\index.js:34:24)
    at startFtpServer (C:\work\xemu\xemu-bsp-list\ftp-srv\bin\index.js:133:21)
    at Object.<anonymous> (C:\work\xemu\xemu-bsp-list\ftp-srv\bin\index.js:11:1)
    at Module._compile (node:internal/modules/cjs/loader:1369:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1427:10)
    at Module.load (node:internal/modules/cjs/loader:1206:32)
    at Module._load (node:internal/modules/cjs/loader:1022:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:135:12)
    at node:internal/main/run_main_module:28:49 {
  code: 'ERR_INVALID_ARG_TYPE'
}

Node.js v20.12.0

src/index.js

@@ -25,8 +25,7 @@ class FtpServer extends EventEmitter {
       greeting: null,
       tls: false,
       timeout: 0
-    }, options);
-
+    }, _.pickBy(options, v => v !== undefined));
     this._greeting = this.setupGreeting(this.options.greeting);
     this._features = this.setupFeaturesMessage();
 
@@ -52,7 +51,7 @@ class FtpServer extends EventEmitter {
       socket.once('close', () => {
         this.emit('disconnect', {connection, id: connection.id, newConnectionCount: Object.keys(this.connections).length});
       })
-      
+
       this.emit('connect', {connection, id: connection.id, newConnectionCount: Object.keys(this.connections).length});
 
       const greeting = this._greeting || [];
@@ -67,7 +66,7 @@ class FtpServer extends EventEmitter {
       this.log.error(err, '[Event] error');
       this.emit('server-error', {error: err});
     });
-    
+
     const quit = _.debounce(this.quit.bind(this), 100);
 
     process.on('SIGTERM', quit);
@@ -138,7 +137,7 @@ class FtpServer extends EventEmitter {
       } catch (err) {
         this.log.error(err, 'Error closing connection', {id});
       }
-      
+
       resolve('Disconnected');
     });
   }