Fixing failing standard tests

Now let's have a look at the errors and see which of them relate to the extension. They might already unlock some of their secrets. All errors that relate, about 157 out of the 176, are similar to the following:

Error Message: Lookup Value Code must have a value in Sales Header: Document Type=Order, No.=1003. It cannot be zero or empty.

With also an Error Call Stack that resembles this one:

SalesPostEvents(CodeUnit 50004).OnBeforePostSalesDocEvent line 3 - LookupValue by fluxxus.nl
"Sales-Post"(CodeUnit 80).OnBeforePostSalesDoc line 2 - Base Application by Microsoft
"Sales-Post"(CodeUnit 80).OnRun(Trigger) line 26 - Base Application by Microsoft
"Library - Sales"(CodeUnit 130509).DoPostSalesDocument line 53 - Tests-TestLibraries by Microsoft
"Library - Sales"(CodeUnit 130509).PostSalesDocument line 2 - Tests-TestLibraries by Microsoft
"ERM VAT Tool - Sales Doc"(CodeUnit 134051).VATToolSalesLineWithZeroOutstandingQty...