[代码完善](v2.5): update EmailServiceImpl.java

close https://github.com/elunez/eladmin/issues/478

eladmin-tools/src/main/java/me/zhengjie/service/impl/EmailServiceImpl.java

@@ -64,7 +64,7 @@ public class EmailServiceImpl implements EmailService {
     @Override
     @Transactional(rollbackFor = Exception.class)
     public void send(EmailVo emailVo, EmailConfig emailConfig){
-        if(emailConfig == null){
+        if(emailConfig.getId() == null){
             throw new BadRequestException("请先配置，再操作");
         }
         // 封装