dynamodb ConditionExpression in Step functions

With the use of aws-step-functions I'm trying to putItem into dynamodb.

Here is an extract of the .yml, which works as intended.

...

AddingURLs:
  Type: Map
  ItemsPath: "$.vidPosts"
  Parameters:
    vidPostsIndex.$: "$$.Map.Item.Index" 
      vidPosts.$: "$$.Map.Item.Value"

  Iterator:
    StartAt: AddingURLIntoDynamoDB
    Comment: Looping over urls and adding them into the db

    States:
      AddingURLIntoDynamoDB:
        Type: Task
        Resource: arn:aws:states:::dynamodb:putItem
        ResultPath: null
        Parameters:
          TableName: my-table-table-name
          Item:
            videoID:
              S.$: "$.vidPosts.[0]"
            urls:
              S.$: "$.vidPosts.[1]"
          ConditionExpression: "attribute_not_exists(videoID)"    

        End: true

  Next: EndStepFunctions

EndStepFunctions:
  Comment: This marks the end of a step functions
  Type: Succeed

But the next time around, when this state is called, if it encounters an entry that already exists, because of, ConditionExpression: "attribute_not_exists(videoID)", as it should, it throws,

{
  executionArn: 'arn:aws:states:us-east-2:aaabbbccc:execution:xxxStateMachine:XXX-YYY-ZZZ',
  stateMachineArn: 'arn:aws:states:us-east-2:aaabbbccc:stateMachine:xxxStateMachine',
  name: '9814ce93-bc42-4f31-a742-089ea7db9ad6',
  status: 'FAILED',
  startDate: 2021-03-18T15:30:45.912Z,
  stopDate: 2021-03-18T15:30:52.386Z,
  input: '{}',
  inputDetails: { included: true },
  error: 'DynamoDB.ConditionalCheckFailedException',
  cause: 'The conditional request failed (Service: AmazonDynamoDBv2; Status Code: 400; Error Code: ConditionalCheckFailedException; Request ID: bfd76f51-567b-439c-9a39-5a1643e75a69; Proxy: null)'
}

My question is within aws-step-functions, how do I make it ignore existing entries but continue with the iterator?

Appreciate any help and thank you in advance.

We just need to catch DynamoDB.ConditionalCheckFailedException exception and move forward, without throwing any error.

What we need is

  "Catch": [
    {
      "ErrorEquals": [
        "DynamoDB.ConditionalCheckFailedException"
      ],
      "Next": "FinalStep"
    }
  ]

Here is full step function.

{
  "StartAt": "put-item",
  "States": {
    "put-item": {
      "Next": "FinalStep",
      "Catch": [
        {
          "ErrorEquals": [
            "DynamoDB.ConditionalCheckFailedException"
          ],
          "Next": "FinalStep"
        }
      ],
      "Type": "Task",
      "Resource": "arn:aws:states:::dynamodb:putItem",
      "Parameters": {
        "Item": {
          "pk": {
            "S": "1"
          },
          "test": {
            "S": "value"
          }
        },
        "TableName": "test",
        "ConditionExpression": "attribute_not_exists(#videoID)",
        "ExpressionAttributeNames": {
          "#videoID": "videoID"
        }
      }
    },
    "FinalStep": {
      "Type": "Pass",
      "End": true
    }
  }
}

Put-item failed with error and still moved to next task.

{
  "Error": "DynamoDB.ConditionalCheckFailedException",
  "Cause": "The conditional request failed (Service: AmazonDynamoDBv2; Status Code: 400; Error Code: ConditionalCheckFailedException; Request ID: xxxx-xxx-xxx-xxx-xxxxx; Proxy: null)"
}