Error: decToBn: Input is not a base-10 integer

[Sniper365]

While creating a new order, It showed me up.

    const order: { order: OrderResponseObject } = await client.private.createOrder(
      {
        side: OrderSide.SELL,
        type: OrderType.LIMIT,
        timeInForce: TimeInForce.GTT,
        postOnly: false,
        size: '1',
        price: '1506',
        limitFee: '0.0',
        expiration: '2023-02-21T21:30:20.200Z',
        market: Market.ETH_USD
      },
      keyPairWithYCoordinate.publicKey
    );

the error;

Error: decToBn: Input is not a base-10 integer
[1]     at decToBn (C:\...\node_modules\@dydxprotocol\starkex-lib\build\src\lib\util.js:74:15)
[1]     at SignableOrder.calculateHash (C:\...\node_modules\@dydxprotocol\starkex-lib\build\src\signable\order.js:64:49)
[1]     at SignableOrder.getHashBN (C:\...\node_modules\@dydxprotocol\starkex-lib\build\src\signable\stark-signable.js:30:39)
[1]     at SignableOrder.sign (C:\...\node_modules\@dydxprotocol\starkex-lib\build\src\signable\stark-signable.js:41:35)
[1]     at Private.createOrder (C:\...\node_modules\@dydxprotocol\v3-client\build\src\modules\private.js:270:42)
[1]     at C:\work\bitoro-perp-v2\dist\index.js:70:47
[1]     at Generator.next (<anonymous>)
[1]     at fulfilled (C:\...\dist\index.js:5:58)
[1]     at processTicksAndRejections (node:internal/process/task_queues:96:5)

it appears in stark-signable.js, the function getHashBN() returns the undefined hashBN.

    async getHashBN() {
        if (this._hashBN === null) {
            console.log('null')
            this._hashBN = await this.calculateHash()
        }
        return this._hashBN;
    }
    /**
     * Sign the message with the given private key, represented as a hex string or hex string pair.
     */
    async sign(privateKey) {
        const hashBN = await this.getHashBN();
        console.log('hashBN------', hashBN)
        const ecSignature = await (0, crypto_1.sign)((0, helpers_1.asEcKeyPair)(privateKey), hashBN);
        return (0, helpers_1.serializeSignature)((0, helpers_1.asSimpleSignature)(ecSignature));
    }

What's the this.calculateHash() function? How it does work?