Why trait for auto generated column is not working?

SQLSTATE[HY000]: General error: 1364 Field 'asset_code' doesn't have a default value 

class Asset extends BaseModel
{
    use AssetCode;

<?php

namespace App\Models\Traits;

trait AssetCode
{
    public static function bootAssetCode(): void
    {
        static::creating(function ($model) {
            if (empty($model->asset_code)) {
                $model->asset_code = self::generateAssetCode();
            }
        });
    }

    protected static function generateAssetCode(): string
    {
        return 'ASSET-' . strtoupper(uniqid());
    }
}