prevent null workstation #'s from passing..

to axios-ntlm

server/model/monitor.js

@@ -279,12 +279,18 @@ class Monitor extends BeanModel {
                     if (this.auth_method === "ntlm") {
                         options.httpsAgent.keepAlive = true;
 
-                        res = await httpNtlm(options, {
+                        let ntlmOptions =
+                            {
                             username: this.basic_auth_user,
                             password: this.basic_auth_pass,
                             domain: this.authDomain,
-                            workstation: this.authWorkstation,
+                        }
-                        });
+
+                        if (this.authWorkstation) {
+                            ntlmOptions.workstation= this.authWorkstation;
+                        }
+
+                        res = await httpNtlm(options, ntlmOptions);
 
                     } else {
                         res = await axiosClient.request(options);