fixes firebase#499

Author: nicolasgarnier

quickstarts/email-users/functions/index.js

@@ -78,7 +78,8 @@ async function sendWelcomeEmail(email, displayName) {
   mailOptions.subject = `Welcome to ${APP_NAME}!`;
   mailOptions.text = `Hey ${displayName || ''}! Welcome to ${APP_NAME}. I hope you will enjoy our service.`;
   await mailTransport.sendMail(mailOptions);
-  return console.log('New welcome email sent to:', email);
+  console.log('New welcome email sent to:', email);
+  return null;
 }
 
 // Sends a goodbye email to the given user.
@@ -93,4 +94,5 @@ async function sendGoodbyeEmail(email, displayName) {
   mailOptions.text = `Hey ${displayName || ''}!, We confirm that we have deleted your ${APP_NAME} account.`;
   await mailTransport.sendMail(mailOptions);
   console.log('Account deletion confirmation email sent to:', email);
+  return null;
 }