fix: 处理null问题

buhuazhen

2026-06-01 facbfd2b1a0eb1ea971b699def8c85a43c5fa7fa

 src/main/java/com/ruoyi/purchase/service/IPurchaseLedgerService.java

@@ -43,4 +43,6 @@
    String getPurchaseNo();

    AjaxResult importData(MultipartFile file);

    PurchaseLedgerDto getPurchaseByCode(PurchaseLedgerDto purchaseLedgerDto);
}