Return email when trying invite by email user already invited by handle

[maxceem]

When we are trying to invite user by "email", when it is already invited by "handle" we get error which is correct. But error doesn't have "email" included for which the error happened:

Response from API looks like this. It doesn't have email, but it should have it.

{
  "success": [],
  "failed": [
    {
      "email": null,
      "message": "User with such email is already invited to this project."
    }
  ]
}

For example, if we invite user by "email" and after try to invite the same user by "handle" then we would get the correct error message with "handle" mentioned in the error:

{
  "success": [],
  "failed": [
    {
      "handle": "pshah_customer",
      "message": "User with such handle is already invited to this project."
    }
  ]
}

See that "handle" is provided so we know which invite failed and has error. We have to fix the same for email.

Note, this doesn't expose PII as we return this error response to the user who invited so they already know the email.