Prevent adding an empty email option in the feedback app in guest mode

chrome/browser/resources/feedback/js/feedback.js

Index: chrome/browser/resources/feedback/js/feedback.js
diff --git a/chrome/browser/resources/feedback/js/feedback.js b/chrome/browser/resources/feedback/js/feedback.js
index 6d8b39c7f939812d2915bcbe0adf9008dfec7df0..cb51b9629910f70da86451009b12e0717b8dffd6 100644
--- a/chrome/browser/resources/feedback/js/feedback.js
+++ b/chrome/browser/resources/feedback/js/feedback.js
@@ -344,6 +344,9 @@ function initialize() {
       });
 
       chrome.feedbackPrivate.getUserEmail(function(email) {
+        // Never add an empty option.
+        if (!email)
+          return;
         var optionElement = document.createElement('option');
         optionElement.value = email;
         optionElement.text = email;