## Is your feature request related to a problem?

Right now, if you try to invite someone who's already invited (or a user) you get the following error message:
![image](https://user-images.githubusercontent.com/1727427/98357556-adff4a80-2025-11eb-9f4d-ba748155d036.png)

## Describe the solution you'd like

The server itself does return a useful error message, so we could just display that

## Describe alternatives you've considered



## Additional context



#### *Thank you* for your feature request – we love each and every one!

posthog/models/organization.py
from typing import Any, Dict, List, Optional, Tuple
from django.conf import settings
from django.db import models, transaction
from django.dispatch import receiver
from django.utils import timezone
from rest_framework import exceptions
from .utils import UUIDModel, sane_repr
try:
    from ee.models.license import License
except ImportError:
    License = None  
class OrganizationManager(models.Manager):
    def bootstrap(
        self, user: Any, *, team_fields: Optional[Dict[str, Any]] = None, **kwargs
    ) -> Tuple["Organization", "OrganizationMembership", Any]:
        """Instead of doing the legwork of creating an organization yourself, delegate the details with bootstrap."""
        from .team import Team  
        with transaction.atomic():
            organization = Organization.objects.create(**kwargs)
            organization_membership = OrganizationMembership.objects.create(
                organization=organization, user=user, level=OrganizationMembership.Level.OWNER
            )
            team = Team.objects.create(organization=organization, **(team_fields or {}))
            user.current_organization = organization
            user.current_team = team
            user.save()
        return organization, organization_membership, team
class Organization(UUIDModel):