FIX: skip email if blank while syncing SSO attributes. (#19939)

Also, return email blank error in `EmailValidator`  when the email is blank.

app/models/discourse_connect.rb

@@ -328,7 +328,7 @@ class DiscourseConnect < DiscourseConnectBase
   def change_external_attributes_and_override(sso_record, user)
     @email_changed = false
 
-    if SiteSetting.auth_overrides_email && user.email != Email.downcase(email)
+    if SiteSetting.auth_overrides_email && email.present? && user.email != Email.downcase(email)
       user.email = email
       user.active = false if require_activation
       @email_changed = true

config/locales/server.en.yml

@@ -2680,6 +2680,7 @@ en:
       must_not_contain_two_special_chars_in_seq: "must not contain a sequence of 2 or more special chars (.-_)"
       must_not_end_with_confusing_suffix: "must not end with a confusing suffix like .json or .png etc."
     email:
+      blank: "can't be blank."
       invalid: "is invalid."
       not_allowed: "is not allowed from that email provider. Please use another email address."
       blocked: "is not allowed."

lib/validators/email_validator.rb

@@ -2,7 +2,10 @@
 
 class EmailValidator < ActiveModel::EachValidator
   def validate_each(record, attribute, value)
-    if !EmailAddressValidator.valid_value?(value)
+    if value.blank?
+      record.errors.add(attribute, I18n.t(:"user.email.blank"))
+      invalid = true
+    elsif !EmailAddressValidator.valid_value?(value)
       if Invite === record && attribute == :email
         record.errors.add(:base, I18n.t(:"invite.invalid_email", email: CGI.escapeHTML(value)))
       else

spec/models/user_spec.rb

@@ -2573,6 +2573,11 @@ RSpec.describe User do
       expect(User.find(user.id).email).to eq(secondary_email_record.email)
       expect(user.secondary_emails.count).to eq(0)
     end
+
+    it "returns error if email is nil" do
+      user.email = nil
+      expect { user.save! }.to raise_error(ActiveRecord::RecordInvalid)
+    end
   end
 
   describe "set_random_avatar" do

spec/requests/admin/users_controller_spec.rb

@@ -1777,6 +1777,26 @@ RSpec.describe Admin::UsersController do
         expect(user.username).to eq("Hokli")
       end
 
+      it "can sync up with the sso without email" do
+        sso.name = "Bob The Bob"
+        sso.username = "bob"
+        sso.email = "bob@bob.com"
+        sso.external_id = "1"
+
+        user =
+          DiscourseConnect.parse(
+            sso.payload,
+            secure_session: read_secure_session,
+          ).lookup_or_create_user
+
+        sso.name = "Bill"
+        sso.username = "Hokli$$!!"
+        sso.email = nil
+
+        post "/admin/users/sync_sso.json", params: Rack::Utils.parse_query(sso.payload)
+        expect(response.status).to eq(200)
+      end
+
       it "should create new users" do
         sso.name = "Dr. Claw"
         sso.username = "dr_claw"