Fix dhcp command

src/CablemodemBundle/Command/DHCPHostCRUDCommand.php

@@ -151,7 +151,7 @@ EOT
             'fixed_address' => $fixedIP ?: null,
             'fixedIP' => $fixedIP ? true : false,
         ];
-        if ($type == 'mta' || $type == 'cpe') {
+        if (isset($hostId) && ($type == 'mta' || $type == 'cpe')) {
             unset($data['mac']);
             $data['host'] = $hostId;