Error with AWS SDK-JS API when Retrieving Seller Partner Product Catalog Inventory – Amazon Web Sevices

I need to retrieve the product catalog of my seller partner on Amazon. Although the API refers to this as "Inventory," I couldn’t find this term in the SDK documentation. I assume that the "Catalog" namespace is the equivalent.

Update:

My custom application requires a list of the following product values:

ASINs
UPCs
SKUs
FNSKUs
I have read the documentation and found an API that returns what I need, which can be found here:
https://developer-docs.amazon.com/sp-api/docs/fba-inventory-api-v1-use-case-guide
According to the documentation, I need to create a signature in order to use the API. However, it is noted that if I use the AWS SDK, I do not need to calculate the signature myself. Therefore, I understand that the best practice is to use the AWS SDK.

I have the necessary IAM role permissions and the SP-API app has been published. I am currently attempting to use the AWS SDK.

I have made some changes based on recommendations, but I am not completely sure what else I need to do. Here is my current code:

```
export const /*bundle */ start = async () => {
    const client = new MarketplaceCatalogClient({
        region: REGION,
        credentials: {
            accessKeyId: ACCESS_KEY_ID,
            secretAccessKey: ACCESS_SECRET_KEY,
        },
    });

    const params = {
        /** input parameters */
    };

    const answer = await client.send(
        new ListEntitiesCommand({ Catalog: "AWSMarketplace", EntityType: "ContainerProduct" })
    );

    console.log(100, answer);
    return answer;
};
```

I got the next answer with "AmiProduct" or "ContainerProduct":

{
  '$metadata': {
    httpStatusCode: 200,
    requestId: '91fc5fed-6cdc-42d6-97ec-1ed3cc9d5796',
    extendedRequestId: undefined,
    cfId: undefined,
    attempts: 1,
    totalRetryDelay: 0
  },
  EntitySummaryList: []
}

I’m having difficulty understanding how to correctly implement this. Any guidance would be greatly appreciated.