[Feature request] - Warning message if no code is specfied for post processing

[trin-wheeler]

Is your feature request related to a problem? Please describe.
When running post-processing with post-processing set to true in the config .xlsx but with no transport code set to true, post processing will start and then instantly end.

Describe the solution you'd like
There should be some warning message for the user to avoid confusion when the config file is incorrectly utilised, similarly to how running of the codes is handled.

Describe alternatives you've considered
Not adding in a warning message.

Additional context
N/A