[Feature] Allow null value for has-delimeter filter (#14)

Co-authored-by: M@ster <[email protected]>

src/Filters/Concerns/HasDelimiter.php

@@ -47,7 +47,7 @@ public function delimiter(string $delimiter): self
     /**
      * Convert the provided value to an array.
      *
-     * @param string|array $value
+     * @param string|array|null $value
      * @return array
      */
     protected function toArray($value): array
@@ -60,6 +60,10 @@ protected function toArray($value): array
             return $value;
         }
 
+        if (\is_null($value)) {
+            return [];
+        }
+
         throw new \LogicException(
             'Expecting filter value to be an array, or a string when a string delimiter is set.'
         );