the tell_pbar() shouldn't forward empty msgs to the progress bar

[AlyaGomaa]

[patel-lay]

Hey @AlyaGomaa, I can work on this. From my understanding it is a simple fix. Steps to fix it

1. Add a condition in tell_pbar() function to check if msg is empty or not before calling pbar_send_pipe function.
2. Modify test_output.py to test this. It will require modification for both test_tell_pbar_empty_message() and test_tell_pbar_none_message().

[AlyaGomaa]

hi @patel-lay yes you're correct