Fix the onFinally callback being called twice in some cases

Fixes #2

index.js

@@ -4,12 +4,14 @@ module.exports = async (
 	promise,
 	onFinally = (() => {})
 ) => {
+	let value;
 	try {
-		const value = await promise;
-		await onFinally();
-		return value;
+		value = await promise;
 	} catch (error) {
 		await onFinally();
 		throw error;
 	}
+
+	await onFinally();
+	return value;
 };

test.js

@@ -44,3 +44,15 @@ test('returning a rejected promise in the callback for an already rejected promi
 		t.is(error, fixtureError);
 	});
 });
+
+test('the onFinally callback is only called once no matter what', async t => {
+	t.plan(1);
+
+	await pFinally(
+		Promise.resolve(),
+		() => {
+			t.pass();
+			throw new Error(); // eslint-disable-line unicorn/error-message
+		}
+	).catch(() => {});
+});