500 in /api/v1/organisations/{organisation_pk}/groups/ when UserPermissionGroup already exists

[sentry]

Sentry Issue: FLAGSMITH-API-5EE

UniqueViolation: duplicate key value violates unique constraint "users_userpermissiongrou_organisation_id_external_198069ed_uniq"
DETAIL:  Key (organisation_id, external_id)=(12171, OP-Flagsmith-CloudPlatform-ProductionTeam) already exists.

  File "django/db/backends/utils.py", line 89, in _execute
    return self.cursor.execute(sql, params)

IntegrityError: duplicate key value violates unique constraint "users_userpermissiongrou_organisation_id_external_198069ed_uniq"
DETAIL:  Key (organisation_id, external_id)=(12171, OP-Flagsmith-CloudPlatform-ProductionTeam) already exists.

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  File "users/views.py", line 232, in perform_create
    serializer.save(organisation_id=self.kwargs["organisation_pk"])