## 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
if not prevalidated:
            self.validate(user=user)
        user.join(organization=self.organization)
        self.delete()
    def is_expired(self) -> bool:
        """Check if invite is older than 3 days."""
        return self.created_at < timezone.now() - timezone.timedelta(3)
    def __str__(self):
        return f"{settings.SITE_URL}/signup/{self.id}"
    __repr__ = sane_repr("organization", "target_email", "created_by")
@receiver(models.signals.pre_delete, sender=OrganizationMembership)
def ensure_organization_membership_consistency(sender, instance: OrganizationMembership, **kwargs):
    save_user = False
    if instance.user.current_organization == instance.organization:
        
        instance.user.current_organization = None
        save_user = True
    if instance.user.current_team is not None and instance.user.current_team.organization == instance.organization:
        
        instance.user.current_team = None
        save_user = True
    if save_user:
        instance.user.save()