MDL-42764 core: added missing string definition

Also changed the string index so it was not
vague. The index 'emailempty' appears as if it
could belong to a validation method for a form.

lang/en/moodle.php

@@ -710,6 +710,7 @@
 If you continue to have difficulty, contact the site administrator.';
 $string['emailtoprivatefiles'] = 'You can also e-mail files as attachments straight to your private files space. Simply attach your files to an e-mail and send it to {$a}';
 $string['emailtoprivatefilesdenied'] = 'Your administrator has disabled the option to upload your own private files.';
+$string['emailuserhasnone'] = 'There is no email address for the user.';
 $string['emailvia'] = '{$a->name} (via {$a->siteshortname})';
 $string['emptydragdropregion'] = 'empty region';
 $string['enable'] = 'Enable';

user/message.html

@@ -42,7 +42,7 @@
                 echo '<td>'.$user->email.'</td><td>';
             }
             if (empty($user->email)) {
-                $error = get_string('emailempty');
+                $error = get_string('emailuserhasnone');
             }
             if (!empty($error)) {
                 echo $OUTPUT->pix_icon('t/emailno', $error);