Update ping.php

Updated error message style
Added new comments to facilitate development
Optimized white spaces
Optimized style

front/php/server/ping.php

@@ -20,7 +20,12 @@ $ip = $_GET['ip'];
 
 // Check if IP is valid
 if (!filter_var($ip, FILTER_VALIDATE_IP)) {
-echo '' . lang('DevDetail_Tab_Tools_Ping_Error') . '';
+	// Error message
+	$output = lang('DevDetail_Tab_Tools_Ping_Error');
+	// Show the result
+	echo "<pre>";
+	echo $output;
+	echo "</pre>";
 	exit;
 }