#521 invoice creation from customer screen broken

<freelock> Just hit "Undefined subroutine &main:: called at bin/oe.pl line 1058."
<freelock> referer: https://mydomain/ledger/customer.pl
<freelock> ehu/ metatrontech: that's trying to create a Sales Order from a customer page --
initially it loads the sales order page with the customer, get that error logged when trying to add a part/line item
<freelock> svn #4038

[Chris Travers]

Works for me