Multi Upload return TRUE

Hi CI Members,

I have issue when I submit form without upload any image and system not detect the input is empty,
But when I remove "[]" in name is work.

I hope CI Members can help me to solve my issue.

Code:

<input type="file" class="form-control-file" id="preview_image" name="preview_image[]" multiple>

PHP Code:

if (isset($_FILES['preview_image']['name'])
        && ($_FILES['preview_image']['name'] != '' || is_array($_FILES['preview_image']['name']) && count($_FILES['preview_image']['name']) > 0)) {
        if (!is_array($_FILES['preview_image']['name'])) {
            
            //Upload Code
    }

    return (bool) $totalUploaded; 


Thanks you...