allow saving false (#98)

boolean false needs to be saved

Author: ngaspari

src/App/Models/Value.php

@@ -101,7 +101,7 @@ public static function validateCreate(Request $request): void
 
         self::filterByAllowedColumn($valueColumn, $request);
 
-        throw_if(!$request->has($valueColumn) || empty($request->get($valueColumn)),
+        throw_if(!$request->has($valueColumn) || is_null($request->get($valueColumn)),
             new Exception("Attribute '$valueColumn' needs to be provided."));
 
         $customField->validate($request->get($valueColumn));