wp-includes/blocks/missing/block.json

{
	"$schema": "https://schemas.wp.org/trunk/block.json",
	"apiVersion": 3,
	"name": "core/missing",
	"title": "Unsupported",
	"category": "text",
	"description": "Your site doesn’t include support for this block.",
	"textdomain": "default",
	"attributes": {
		"originalName": {
			"type": "string"
		},
		"originalUndelimitedContent": {
			"type": "string"
		},
		"originalContent": {
			"type": "string",
			"source": "raw"
		}
	},
	"supports": {
		"className": false,
		"customClassName": false,
		"inserter": false,
		"html": false,
		"reusable": false,
		"interactivity": {
			"clientNavigation": true
		}
	}
}