-    $order->{delivered_amount}  = sum map { $self->sum_relevant_items(order => $order, other => $_, by_order => 1)    } @delivery_orders;
-    $order->{billed_amount}     = sum map { $self->sum_relevant_items(order => $order, other => $_)                   } @invoices;
-    $order->{paid_amount}       = sum map { $_->paid * $_->netamount / (($_->amount * 1) || ($_->netamount * 1) || 1) } @invoices;
-    my $billed_amount           = sum map { $_->netamount                                                             } @invoices;
+    $order->{delivered_amount}  = sum(map { $self->sum_relevant_items(order => $order, other => $_, by_order => 1)    } @delivery_orders) // 0;
+    $order->{billed_amount}     = sum(map { $self->sum_relevant_items(order => $order, other => $_)                   } @invoices)        // 0;
+    $order->{paid_amount}       = sum(map { $_->paid * $_->netamount / (($_->amount * 1) || ($_->netamount * 1) || 1) } @invoices)        // 0;
+    my $billed_amount           = sum(map { $_->netamount                                                             } @invoices)        // 0;