Deleted invitation link results in 404

Summary

When a user project invitation is removed, the invitation link becomes invalid and visiting it result in a 404.

Steps to reproduce

• Project owner

  1. Navigate to project=>members
  2. Add a new user to a project using email address "test@example.org"
  3. Delete the invitation

• Invited member

  1. Click the "accept invitation" link

Expected behavior

Redirected to the login page with a flash message.

Actual behavior

404 page