Do not show error on dhcp status

lib/network.js

@@ -326,25 +326,27 @@ function getInterfaceConnectionName(interfaceName) {
 }
 
 function getDHCPstatus(connectionName) {
-  const cmd = `nmcli connection show "${connectionName}" \| grep ipv4.method;`;
-  try {
-    console.log(1);
-    const result = execSync(cmd).toString();
-    console.log(2);
-    const resultFormat = result.replace(/\s+/g,' ').trim();
-    
-    let dhcStatus = resultFormat.split(" ").slice(1).toString();
-    switch (dhcStatus) {
-      case 'auto':
-        dhcStatus = true;
-        break;
-    
-      default:
-        dhcStatus = false;
-        break;
+  if(connectionName) {
+    const cmd = `nmcli connection show "${connectionName}" \| grep ipv4.method;`;
+    try {
+      const result = execSync(cmd).toString();
+      const resultFormat = result.replace(/\s+/g,' ').trim();
+      
+      let dhcStatus = resultFormat.split(" ").slice(1).toString();
+      switch (dhcStatus) {
+        case 'auto':
+          dhcStatus = true;
+          break;
+      
+        default:
+          dhcStatus = false;
+          break;
+      }
+      return dhcStatus;
+    } catch (e) {
+      return 'Unknow';
     }
-    return dhcStatus;
-  } catch (e) {
+  } else {
     return 'Unknow';
   }
 }