Template:Tuple error

╷
│ Error: Invalid index
│
│   on api.tf line 15, in resource "aws_ecs_service" "your_service":
│   15:     target_group_arn = aws_lb_target_group.your_tg[0].arn
│     ├────────────────
│     │ aws_lb_target_group.your_tg is empty tuple
│
│ The given key does not identify an element in this collection value: the
│ collection has no elements.
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