Issue Summary

While using atlassian/aws-ecs-deploy in the Pipeline step with AWS_OIDC_ROLE_ARN and AWS_DEFAULT_REGION and without specifying the any value for the AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY variables, it returns the following error:

bash: <variable name>: unbound variable 

Steps to Reproduce

1. Define the following variables and assign values to them (Workspace/Repository/Deployment) in the Pipeline 
   1. AWS_DEFAULT_REGION
   2. AWS_OIDC_ROLE_ARN
2. Use the following script in the Pipeline

   pipelines:
     default:
         - step:
             name: Test
             oidc: true
             script:
               - set -eou pipefail
               - pipe: atlassian/aws-ecs-deploy:1.9.0
                 variables:
                  AWS_DEFAULT_REGION: ${AWS_DEFAULT_REGION}
                  AWS_OIDC_ROLE_ARN: ${AWS_ROLE_ARN}
                  CLUSTER_NAME: ${CLUSTER_NAME}
                  SERVICE_NAME: ${BITBUCKET_REPO_SLUG}
                  TASK_DEFINITION: scripts/ecs/${BITBUCKET_REPO_SLUG}-task-def.json
                  FORCE_NEW_DEPLOYMENT: 'true'
   

3. Since the set -eou pipefail command has -u option set, it expects all the variables to have the default values

Expected Results

The Pipeline should be successful without any issues

Actual Results

Since the following variables doesn't have any default value set in the Pipeline, it return with the error:

1. AWS_ACCESS_KEY_ID
2. AWS_SECRET_ACCESS_KEY

Workaround

Specify empty as the default value for the AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY in the Pipe definition

pipelines:
  default:
      - step:
          name: Test
          oidc: true
          script:
            - set -eou pipefail
            - pipe: atlassian/aws-ecs-deploy:1.9.0
              variables:
               AWS_DEFAULT_REGION: ${AWS_DEFAULT_REGION}
               AWS_OIDC_ROLE_ARN: ${AWS_ROLE_ARN}
               CLUSTER_NAME: ${CLUSTER_NAME}
               SERVICE_NAME: ${BITBUCKET_REPO_SLUG}
               TASK_DEFINITION: scripts/ecs/${BITBUCKET_REPO_SLUG}-task-def.json
               FORCE_NEW_DEPLOYMENT: 'true'
               AWS_ACCESS_KEY_ID: ''
               AWS_SECRET_ACCESS_KEY: ''