Error: Unexpected resource instance key

Error: Unexpected resource instance key

╷
│ Error: Unexpected resource instance key
│
│   on nats.tf line 5, in resource "aws_ecs_service" "your_service":
│    5:   task_definition = "${aws_ecs_task_definition.your_task[0].family}:${aws_ecs_task_definition.your_task[0].revision}"
│
│ Because aws_ecs_task_definition.your_task does not have "count" or
│ "for_each" set, references to it must not include an index key. Remove the
│ bracketed index to refer to the single instance of this resource.

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