any added or modified xpath express by deviation is not checked whether the reference is correct

[lllyfeng]

I add a must expression to a target node, but the expression is wrong. but it's complied successfully by pyang for example: the original module:

module huawei-devm {
  namespace "urn:huawei:yang:huawei-devm";
  prefix devm;
  organization
    "Huawei Technologies Co., Ltd.";
  contact
    "Huawei Industrial Base
     Bantian, Longgang
     Shenzhen 518129
     People's Republic of China
     Website: http://www.huawei.com
     Email: support@huawei.com";
  description
    "Global configuration.";
  revision 2020-08-07 {
    description
      "Add container active-hardware-alarm-infos and history-hardware-alarm-infos.";
    reference
      "Huawei private.";
  }
  revision 2020-06-04 {
    description
      "Add units of up-to-last-clean, alarm-exist-days, enable-transmission-delay and physical-bandwidth.
       Modify operation-exclude for list chassis, mpu-board, lpu-board, card and port.
       Delete leaf current-id, next-id, current-run-mode and next-run-mode.
       Modify the description of port position.";
    reference
      "Huawei private.";
  }

  container devm {
    description
      "Global configuration.";
    container mpu-boards {
      description
        "List of MPU.";
      list mpu-board {
        key "position";
        description
          "Specify MPU.";
        leaf position {
          type string {
            length "1..32";
          }
          description
            "MPU position.";
        }
        leaf index {
          type uint32;
          config false;
          description
            "MPU index.";
        }
        leaf board-type {
          type string {
            length "0..30";
          }
          config false;
          description
            "MPU type.";
        }
        leaf sdram-size {
          type uint32;
          units MByte;
          config false;
          description
            "SDRAM size.";
        }
        leaf nvram-size {
          type uint32;
          units MByte;
          config false;
          description
            "NVRAM size.";
        }
        leaf flash-size {
          type uint32;
          units MByte;
          config false;
          description
            "Flash size.";
        }
      }
    }
  }
}

and my deviation module:

module huawei-devm-deviations-NE8000M8M14 {
  namespace "urn:huawei:yang:huawei-devm-deviations-NE8000M8M14";
  prefix devm-devs-NE8000M8M14;

  import huawei-devm {
    prefix devm;
  }

  organization
    "Huawei Technologies Co., Ltd.";
  contact
    "Huawei Industrial Base
     Bantian, Longgang
     Shenzhen 518129
     People's Republic of China
     Website: http://www.huawei.com
     Email: support@huawei.com";
  description
    "Global Configuration.";

  revision 2019-04-03 {
    description
      "Initial revision.";
    reference "Huawei private.";
  }

  deviation "/devm:devm/devm:mpu-boards/devm:mpu-board/devm:sdram-size" {
    deviate add {
       must "../devm:abc > ../devm:nvram-size";
    }
  }

}

NOTE: the abc node is not defined.