fix: make sure that split lines are expanded for line service

Author: turip

openmeter/billing/service/lineservice/linebase.go

@@ -106,6 +106,13 @@ func (l lineBase) Validate(ctx context.Context, invoice *billing.Invoice) error
 		}
 	}
 
+	// Expanding the split lines are mandatory for the lineservice to work properly.
+	if l.line.SplitLineGroupID != nil && l.line.SplitLineHierarchy == nil {
+		return billing.ValidationError{
+			Err: fmt.Errorf("split line group[%s] has no hierarchy expanded hierarchy", *l.line.SplitLineGroupID),
+		}
+	}
+
 	return nil
 }
 
@@ -114,10 +121,6 @@ func (l lineBase) IsLastInPeriod() bool {
 		return true
 	}
 
-	if l.line.SplitLineHierarchy == nil {
-		return true
-	}
-
 	if l.line.SplitLineHierarchy.Group.ServicePeriod.End.Equal(l.line.Period.End) {
 		return true
 	}
@@ -130,10 +133,6 @@ func (l lineBase) IsFirstInPeriod() bool {
 		return true
 	}
 
-	if l.line.SplitLineHierarchy == nil {
-		return true
-	}
-
 	if l.line.SplitLineHierarchy.Group.ServicePeriod.Start.Equal(l.line.Period.Start) {
 		return true
 	}