Index: openacs-4/packages/acs-subsite/www/members/user-new.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-subsite/www/members/user-new.tcl,v
diff -u -N -r1.13 -r1.14
--- openacs-4/packages/acs-subsite/www/members/user-new.tcl	30 May 2018 11:50:38 -0000	1.13
+++ openacs-4/packages/acs-subsite/www/members/user-new.tcl	28 Sep 2018 18:43:09 -0000	1.14
@@ -5,7 +5,7 @@
     @creation-date 2003-06-02
     @cvs-id $Id$
 } {
-    email:trim
+    {email:trim ""}
 }
 
 subsite::assert_user_may_add_member
@@ -24,47 +24,69 @@
 set page_title "Invite Member to [ad_conn instance_name]"
 set context [list [list "." "Members"] "Invite"]
 
-
+#
 # Check if email is already known on the system
+#
 set party_id [party::get_by_email -email $email]
 
 if { $party_id ne "" } {
+    #
     # Yes, is it a user?
+    #
     set user_p [db_0or1row is_user { select 1 from users where user_id = :party_id }]
 
     if { !$user_p } {
         # This is a party, but it's not a user
 
         acs_object_type::get -object_type [acs_object_type $party_id] -array object_type
+        #
         # TODO: Move this to the form, by moving the form to an include template
+        #
         ad_return_complaint 1 "<li>This email belongs to a $object_type(pretty_name) on the system. We cannot create a new user with this email."
         ad_script_abort
-    } else {
-        # Already a user, but not a member of this subsite, and may not be a member of the main site (registered users)
 
+    } else {
+        #
+        # Already a user, but not a member of this subsite, and may
+        # not be a member of the main site (registered users)
+        #
         # We need to know if we're on the main site below
+        #
         set main_site_p [string equal [site_node::get_url -node_id [ad_conn node_id]] "/"]
-        
+
         # Check to see if the user is a member of the main site (registered user)
         set registered_user_p [acs_user::registered_user_p -user_id $party_id]
 
         if { !$registered_user_p } {
+            #
             # User exists, but is not member of main site. Requires SW-admin to remedy.
+            #
             if { [acs_user::site_wide_admin_p] } {
                 set main_site_id [site_node::get_element -url / -element object_id]
                 group::add_member \
                     -group_id [application_group::group_id_from_package_id -package_id $main_site_id] \
                     -user_id $party_id
             } else {
+                #
                 # TODO: Move this to the form, by moving the form to an include template
+                #
                 ad_return_complaint 1 "<li>User has an acccount on the system, but has been removed from the main site. Only a site-wide administrator can re-add the user."
                 ad_script_abort
             }
         }
 
+        #
         # The user is now a registered user (member of main site)
+        #
         if { $main_site_p } {
+            #
             # Already a member.
+            #
+            #
+            # TODO: Move this to the form, by moving the form to an include template
+            #
+            ad_return_complaint 1 "<li>User is already a registered user (member of the main site)."
+            ad_script_abort
         } else {
             group::add_member \
                 -group_id $group_id \