fix(ui): allow unreacting from comment popover

- fix selectors for hasReacted
- don't send empty HTML on reaction errors
- add E2E test

tests/e2e/reaction-selectors.test.e2e.js

@@ -0,0 +1,65 @@
+// @ts-check
+import {test, expect} from '@playwright/test';
+import {login_user, load_logged_in_context} from './utils_e2e.js';
+
+test.beforeAll(async ({browser}, workerInfo) => {
+  await login_user(browser, workerInfo, 'user2');
+});
+
+const assertReactionCounts = (comment, counts) =>
+  expect(async () => {
+    await expect(comment.locator('.reactions')).toBeVisible();
+
+    const reactions = Object.fromEntries(
+      await Promise.all(
+        (
+          await comment
+            .locator(`.reactions [role=button][data-reaction-content]`)
+            .all()
+        ).map(async (button) => [
+          await button.getAttribute('data-reaction-content'),
+          parseInt(await button.locator('.reaction-count').textContent()),
+        ]),
+      ),
+    );
+    return expect(reactions).toStrictEqual(counts);
+  }).toPass();
+
+async function toggleReaction(menu, reaction) {
+  await menu.evaluateAll((menus) => menus[0].focus());
+  await menu.locator('.add-reaction').click();
+  await menu.locator(`[role=menuitem][data-reaction-content="${reaction}"]`).click();
+}
+
+test('Reaction Selectors', async ({browser}, workerInfo) => {
+  const context = await load_logged_in_context(browser, workerInfo, 'user2');
+  const page = await context.newPage();
+
+  const response = await page.goto('/user2/repo1/issues/1');
+  await expect(response?.status()).toBe(200);
+
+  const comment = page.locator('.comment#issuecomment-2').first();
+
+  const topPicker = comment.locator('.actions [role=menu].select-reaction');
+  const bottomPicker = comment.locator('.reactions').getByRole('menu');
+
+  await assertReactionCounts(comment, {'laugh': 2});
+
+  await toggleReaction(topPicker, '+1');
+  await assertReactionCounts(comment, {'laugh': 2, '+1': 1});
+
+  await toggleReaction(bottomPicker, '+1');
+  await assertReactionCounts(comment, {'laugh': 2});
+
+  await toggleReaction(bottomPicker, '-1');
+  await assertReactionCounts(comment, {'laugh': 2, '-1': 1});
+
+  await toggleReaction(topPicker, '-1');
+  await assertReactionCounts(comment, {'laugh': 2});
+
+  await comment.locator('.reactions [role=button][data-reaction-content=laugh]').click();
+  await assertReactionCounts(comment, {'laugh': 1});
+
+  await toggleReaction(topPicker, 'laugh');
+  await assertReactionCounts(comment, {'laugh': 2});
+});