further bug fixes relating to Si problem.

Description

This merge request fixes some crashes, resulting from calculating the currents, when not necessary. The current calculator implied complex orbitals, which lead to crashes (with device_packed batches) when otherwise requesting real orbitals.

News snippet

Bug fix for calculations with real orbitals.

Checklist

• I have checked that my code follows the Octopus coding standards
• I have added tests for all the new features added in this request.