Prevent more PHP warnings (#7609)

* Prevent more PHP warnings

* Update call_broadcast_edit.php

* Update call_center_agent_edit.php

* Update call_flow_edit.php

* Update call_center_queue_edit.php

* Update conference_center_edit.php

* Update conference_room_edit.php

* Update conference_control_detail_edit.php

* Update conference_control_edit.php

* Update conference_profile_edit.php

* Update conference_edit.php

* Update conference_profile_param_edit.php

* Update destination_edit.php

* Update device_edit.php

* Update dialplan_inbound_add.php

* Update dialplan_outbound_add.php

* Update dialplan_add.php

* Update dialplan_edit.php

* Update event_guard_logs.php

* Update extension_setting_edit.php

* Update extension_edit.php

* Update fax_edit.php

* Update fifo_edit.php

* Update ivr_menu_edit.php

* Update phrase_edit.php

* Update ring_group_edit.php

* Update sip_profile_edit.php

* Update stream_edit.php

* Update time_condition_edit.php

* Update var_edit.php

* Update voicemail_edit.php

* Update xml_cdr_search.php

* Update dashboard_widget_edit.php

* Update domain_edit.php

* Update group_edit.php

* Update user_edit.php

* Update gateway_edit.php

app/conferences/conference_edit.php

@@ -313,7 +313,9 @@
 	}
 
 //set the defaults
-	if (empty($conference_context)) { $conference_context = $_SESSION['domain_name']; }
+	$conference_profile = $conference_profile ?? 'default';
+	$conference_context = $conference_context ?? $_SESSION['domain_name'];
+	$conference_enabled = $conference_enabled ?? true;
 
 //get the conference profiles
 	$sql = "select * ";
@@ -342,9 +344,6 @@
 	$users = $database->select($sql, $parameters ?? null, 'all');
 	unset($sql, $parameters);
 
-//set the default
-	if (empty($conference_profile)) { $conference_profile = "default"; }
-
 //create token
 	$object = new token;
 	$token = $object->create($_SERVER['PHP_SELF']);