save-test-data.php: Print a message when we encounter a bad module name (#8274)

* Print a message when we encounter a bad module name (likely a typo)

* Raise exception for invalid module name and handle it.

LibreNMS/Exceptions/InvalidModuleException.php

@@ -0,0 +1,30 @@
+<?php
+/**
+ * InvalideModuleException.php
+ *
+ * Thrown when the given name isn't a valid discovery or poller module
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @package    LibreNMS
+ * @link       http://librenms.org
+ * @copyright  2018 Tony Murray
+ * @author     Tony Murray <murraytony@gmail.com>
+ */
+
+namespace LibreNMS\Exceptions;
+
+class InvalidModuleException extends \Exception
+{
+}