Remove strict true === $user['showEmail'] on preSubmit

Author: jbdelhommeau

form/events.rst

@@ -287,7 +287,7 @@ Creating and binding an event listener to the form::
             // checks whether the user has chosen to display their email or not.
             // If the data was submitted previously, the additional value that is
             // included in the request variables needs to be removed.
-            if (true === $user['showEmail']) {
+            if (isset($user['showEmail']) && $user['showEmail']) {
                 $form->add('email', EmailType::class);
             } else {
                 unset($user['email']);
@@ -383,7 +383,7 @@ Consider the following example of a form event subscriber::
             // checks whether the user has chosen to display their email or not.
             // If the data was submitted previously, the additional value that
             // is included in the request variables needs to be removed.
-            if (true === $user['showEmail']) {
+            if (isset($user['showEmail']) && $user['showEmail']) {
                 $form->add('email', EmailType::class);
             } else {
                 unset($user['email']);