Months with no invoices should not show up in Reports drop-down

The default reports are displayed month-wise. In the drop-down (image below), the previous six months are displayed by default. If a month doesn't have any received and sent invoices, it shouldn't get displayed at all in the drop-down.


Start at the Reports drop-down entry point and trace how the previous six months and invoice data are assembled. Verify the behavior with months containing no received or sent invoices; done means those empty months no longer appear while months with invoices remain available.

Written by the indexing model from the issue text.