always create outro method for top-level block - fixes #1470

src/compile/dom/index.ts

@@ -55,6 +55,10 @@ export default function dom(
 	compiler.fragment.build();
 	const { block } = compiler.fragment;
 
+	if (compiler.options.nestedTransitions) {
+		block.hasOutroMethod = true;
+	}
+
 	// prevent fragment being created twice (#1063)
 	if (options.customElement) block.builders.create.addLine(`this.c = @noop;`);
 

test/runtime/samples/if-block-component-without-outro/Widget.html

@@ -0,0 +1 @@
+<div>A wild component appears</div>

test/runtime/samples/if-block-component-without-outro/_config.js

@@ -0,0 +1,15 @@
+export default {
+	skipIntroByDefault: true,
+	nestedTransitions: true,
+
+	data: {
+		foo: true,
+	},
+
+	html: '<div>A wild component appears</div>',
+
+	test(assert, component, target) {
+		component.set({ foo: false });
+		assert.htmlEqual(target.innerHTML, '');
+	},
+};

test/runtime/samples/if-block-component-without-outro/main.html

@@ -0,0 +1,11 @@
+{#if foo}
+	<Widget/>
+{/if}
+
+<script>
+	export default {
+		components: {
+			Widget: './Widget.html'
+		}
+	};
+</script>