Invoice requires an accounting code when "Export to accounting" is false

How to reproduce:
Create invoice
Use vendor with no accounting code information
DO NOT toggle "Export to accounting"
create invoice line
Approve invoice

Actual: Invoice is NOT approved and message does NOT alert the user that it is the accounting code that is missing

Expected: If Export to accounting IS NOT active than system should not require accounting code to approve invoice. IF "Export to accounting" is active error message should be shown to user when trying to approve the indicates the "Invoice can not be approved, because it requires an accounting code to be export to accounting.