Fix PHP notice shown when rendering a navigation link block (#28999)

* Fix undefined index issue in navigation link rendering

* Add test for plain link block rendering

packages/block-library/src/navigation-link/index.php

@@ -106,7 +106,9 @@ function block_core_navigation_link_render_submenu_icon() {
 function render_block_core_navigation_link( $attributes, $content, $block ) {
 	// Don't render the block's subtree if it is a draft.
 	if (
-		isset( $attributes['id'] ) && is_numeric( $attributes['id'] ) &&
+		isset( $attributes['id'] ) &&
+		is_numeric( $attributes['id'] ) &&
+		isset( $attributes['type'] ) &&
 		( 'post' === $attributes['type'] || 'page' === $attributes['type'] )
 	) {
 		$post = get_post( $attributes['id'] );

phpunit/class-block-library-navigation-link-test.php

@@ -146,4 +146,24 @@ function test_returns_link_for_category() {
 			) !== false
 		);
 	}
+
+	function test_returns_link_for_plain_link() {
+		$parsed_blocks = parse_blocks(
+			'<!-- wp:navigation-link {"label":"My Website","url":"https://example.com"} /-->'
+		);
+		$this->assertEquals( 1, count( $parsed_blocks ) );
+
+		$navigation_link_block = new WP_Block( $parsed_blocks[0], array() );
+		$this->assertEquals(
+			true,
+			strpos(
+				gutenberg_render_block_core_navigation_link(
+					$navigation_link_block->attributes,
+					array(),
+					$navigation_link_block
+				),
+				'My Website'
+			) !== false
+		);
+	}
 }