registerPlugin should fix Exception

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in vendor/smarty/smarty/src/Smarty.php class_exists (line 752)

* @api Smarty::registerPlugin() */ public function registerPlugin($type, $name, $callback, $cacheable = true) { if (isset($this->registered_plugins[$type][$name])) { throw new Exception("Plugin tag '{$name}' already registered"); } elseif (!is_callable($callback) && !class_exists($callback)) { throw new Exception("Plugin '{$name}' not callable"); } else { $this->registered_plugins[$type][$name] = [$callback, (bool)$cacheable]; } return $this;

HTTP 500 Internal Server Error:
class_exists(): Argument #1 ($class) must be of type string, array given

[starline]

How to catch

use:
$this->smarty->registerPlugin(Smarty::PLUGIN_MODIFIER, $name, [$instance, $function_name]);
and function doesn't exist

I expect to get an exception. but I've gotten the error