UX: improve error message for already logged in users (#11020)

app/controllers/invites_controller.rb

@@ -254,7 +254,7 @@ class InvitesController < ApplicationController
 
   def ensure_not_logged_in
     if current_user
-      flash[:error] = I18n.t("login.already_logged_in", current_user: current_user.username)
+      flash[:error] = I18n.t("login.already_logged_in")
       render layout: 'no_ember'
       false
     end

config/locales/server.en.yml

@@ -2452,7 +2452,7 @@ en:
     missing_user_field: "You have not completed all the user fields"
     auth_complete: "Authentication is complete."
     click_to_continue: "Click here to continue."
-    already_logged_in: "Oops, looks like you are attempting to accept an invitation for another user. If you are not %{current_user}, please log out and try again."
+    already_logged_in: "Sorry! This invitation is intended for new users, who do not already have an existing account."
     second_factor_title: "Two-Factor Authentication"
     second_factor_description: "Please enter the required authentication code from your app:"
     second_factor_backup_description: "Please enter one of your backup codes:"

spec/requests/invites_controller_spec.rb

@@ -10,6 +10,15 @@ describe InvitesController do
     fab!(:invite) { Fabricate(:invite) }
     fab!(:user) { Fabricate(:coding_horror) }
 
+    it 'does not work for logged in users' do
+      sign_in(Fabricate(:user))
+      get "/invites/#{invite.invite_key}"
+
+      expect(response.status).to eq(200)
+      body = response.body
+      expect(CGI.unescapeHTML(body)).to include(I18n.t("login.already_logged_in"))
+    end
+
     it "returns error if invite not found" do
       get "/invites/nopeNOPEnope"