try/finally around directive cleanup

Author: tombl

src/client/parts.ts

@@ -296,8 +296,11 @@ export function create_directive_part(node: Node): Part {
 	return fn => {
 		if (prev_fn === fn) return
 		assert(typeof fn === 'function' || fn == null)
-		cleanup?.()
-		cleanup = fn?.(node)
+		try {
+			cleanup?.()
+		} finally {
+			cleanup = fn?.(node)
+		}
 		prev_fn = fn
 	}
 }

src/client/tests/directives.test.ts

@@ -243,3 +243,31 @@ test('same directive function is not re-invoked or cleaned up', () => {
 	root.render(template(null, null))
 	assert_deep_eq(sequence, ['stable cleanup', 'unstable cleanup'])
 })
+
+test('cleanup can throw and next directive will still run', () => {
+	const { root, el } = setup()
+
+	const template = (d: Directive | null) => html`<div ${d}>Hello, world!</div>`
+
+	const oops = new Error('oops')
+
+	root.render(
+		template(() => () => {
+			throw oops
+		}),
+	)
+
+	let caught
+	try {
+		root.render(
+			template(node => {
+				;(node as HTMLElement).style.color = 'red'
+			}),
+		)
+	} catch (error) {
+		caught = error
+	}
+
+	assert_eq(caught, oops)
+	assert_eq(el.querySelector('div')!.style.cssText, 'color: red;')
+})