Ensure there is no policy with an invalid principal key for Amazon Simple Notification Service (SNS) Topic

Setting a Principal in an access policy will effectively grant users, accounts, or services with access to each SNS Topic. For more information on how to properly assign a Principal within the SNS policy, see the AWS documentation.
References:
https://docs.aws.amazon.com/sns/latest/dg/sns-access-policy-use-cases.html

In AWS Console -

1. Sign in to the AWS console and go to the SNS console.
2. In the Navigation pane, select Topics.
3. In the list of Topics, select the Topic to edit.
4. Expand the Access section, and then edit the policy.
5. Select Save changes.

In Terraform -

1. Review the policy attached to the aws_sns_topic resource and ensure necessary changes are made.

References:
https://docs.aws.amazon.com/sns/latest/dg/sns-access-policy-use-cases.html
https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/sns_topic