Context

when estimating instant fees, we're using a new service, and there we're assuming that amount of units is sent in the event, but some aggregation types do not contain units in properties, because we consider the whole event as unit

Description

• If charge billable_metric does not support field name, we should consider the whole event as one unit
• small additional fix: when generating progressive billing invoice, this process can fail because of idempotency, if it was triggered multiple times, so we don't want to send the webhook if the invoice generation failed