Steps to reproduce:

1. Create a new content type with two fields: Text Line (not required); Image Asset (not required);
2. Create a new content item with a new content type. Specify the name and do not upload or select image;
3. Click on preview and then click back.

Actual result: Preview is empty. When going back there is an error message.
Expected result: there is a preview. There is no error message.

Error message text:

Type error: Argument 1 passed to eZ\Publish\Core\MVC\Symfony\FieldType\ImageAsset\ParameterProvider::loadContentInfo() must be of the type integer, null given, called in /var/www/vendor/ezsystems/ezpublish-kernel/eZ/Publish/Core/MVC/Symfony/FieldType/ImageAsset/ParameterProvider.php on line 45 [in vendor/ezsystems/ezpublish-kernel/eZ/Publish/Core/MVC/Symfony/FieldType/ImageAsset/ParameterProvider.php:69]