support Each blocks without an item

Author: baseballyama

packages/eslint-plugin-svelte/src/rules/require-each-key.ts

@@ -15,7 +15,9 @@ export default createRule('require-each-key', {
 	create(context) {
 		return {
 			SvelteEachBlock(node: AST.SvelteEachBlock) {
-				if (node.key == null) {
+				// NO need a `key` if an each blocks without an item
+				// see: https://svelte.dev/docs/svelte/each#Each-blocks-without-an-item
+				if (node.context != null && node.key == null) {
 					context.report({
 						node,
 						messageId: 'expectedKey'

packages/eslint-plugin-svelte/tests/fixtures/rules/require-each-key/valid/svelte5/_requirements.json

@@ -0,0 +1,3 @@
+{
+	"svelte": ">=5.0.0-0"
+}

packages/eslint-plugin-svelte/tests/fixtures/rules/require-each-key/valid/svelte5/each-blocks-without-an-item-input.svelte

@@ -0,0 +1,7 @@
+<div class="chess-board">
+	{#each { length: 8 }, rank}
+		{#each { length: 8 }}
+			{rank}
+		{/each}
+	{/each}
+</div>