Fehler basierte auf dem falsch verstandenem Konzept von BankTransactions
Entsprechend beim Dialogbuchungen hart abfangen
die "guru meditation error: Can only assign amount to one bank account booking" if scalar @{ $payment } > 1;
# credit/debit * -1 matches the sign for bt.amount and bt.invoice_amount
+ die "Can only assign the full bank amount to a single general ledger booking" unless $bt->amount == $payment->[0]->amount * -1;
$bt->update_attributes(invoice_amount => $bt->invoice_amount + ($payment->[0]->amount * -1));
# create record_link