bugfix 余额支付退款时空指针异常

jsowell-pile/src/main/java/com/jsowell/pile/service/impl/MemberWalletInfoServiceImpl.java

@@ -46,7 +46,15 @@ public class MemberWalletInfoServiceImpl implements MemberWalletInfoService {
 
     @Override
     public MemberWalletInfo selectByMemberId(String memberId, String merchantId) {
-        return memberWalletInfoMapper.selectByMemberId(memberId, merchantId);
+        List<MemberWalletInfo> list = memberWalletInfoMapper.selectByMemberIdList(memberId, merchantId);
+        if (CollectionUtils.isEmpty(list)) {
+            return null;
+        }
+        // 优先返回 merchantId 不为空的记录，避免脏数据干扰
+        return list.stream()
+                .filter(w -> w.getMerchantId() != null)
+                .findFirst()
+                .orElse(list.get(0));
     }
 
     @Override