Fix instantiation check for Cloack

src/Error/Cloak.php

@@ -7,6 +7,7 @@
 use Closure;
 use ErrorException;
 
+use ValueError;
 use function error_reporting;
 use function restore_error_handler;
 use function set_error_handler;
@@ -18,14 +19,22 @@ class Cloak
     public const THROW = 2;
 
     protected static bool $useException = false;
+
     protected CloakedErrors $errors;
     protected readonly ErrorLevel $errorLevel;
 
+    /**
+     * @throws ValueError
+     */
     public function __construct(
         protected readonly Closure $closure,
         protected readonly int $onError = self::FOLLOW_ENV,
         ErrorLevel|string|int|null $errorLevel = null
     ) {
+        if (!in_array($this->onError, [self::SILENT, self::THROW, self::FOLLOW_ENV], true)) {
+            throw new ValueError('The `onError` value is invalid; expect one of the `' . self::class . '` constants.');
+        }
+
         $this->errorLevel = match (true) {
             $errorLevel instanceof ErrorLevel => $errorLevel,
             is_string($errorLevel) => ErrorLevel::fromName($errorLevel),