[Bug]: Not in customer group promotion rule not working on logged-in customer

[pepijn-vanvlaanderen]

Reproduced on Medusa v2.11.3

What happended?

1. Create a promotion rule with a condition: customer group not in GroupX.
2. Then log in as customer that has no customer groups assigned
3. Try to applye the promotion
4. Throws error and promotion is not being applied.

Expected behavior

Since the customer has no customer group, the customer is also not in GroupX and the promotion should be applied.

Actual behavior

No promotion applied.

Note, when you add the customer to GroupY (so different then the not in group) for example it does work. So it seems in the promotion module when the customer group relation is absent this throws an issue.