REG-34: Fix yarn lint errors

Author: bdsl

steps/donation.js

@@ -29,7 +29,7 @@ BeforeAll(() => {
 // Steps
 Given(
     /^that I am on my chosen ([a-zA-Z]+)-enabled charity's Donate page$/,
-    async (psp) => {
+    async () => {
         page.nextStepIndex = 0;
         await page.open();
         await page.checkReady();

support/mailtrap.js

@@ -87,7 +87,7 @@ export async function checkAnEmailBodyContainsText(searchText, toEmailAddress) {
  *
  * @param {string} searchText   Text to expect in latest subject line.
  * @param {string} toEmailAddress Only find emails addressed to this account
- * @returns {Promise<void>}
+ * @returns {Promise<void>} Promise that resolves when check is done.
  */
 export async function checkAnEmailSubjectContainsText(searchText, toEmailAddress) {
     const messages = await getLatestMessages(toEmailAddress);