Unassigned variable in probabilistic GSP

[dfulu]

On the Forecast page, if you select GSP ID 1-317 (i.e. not national) and select the pvnet_v2 model the following error message is displayed:

UnboundLocalError: local variable 'show_prob' referenced before assignment
Traceback:
File "/usr/local/lib/python3.10/site-packages/streamlit/runtime/scriptrunner/script_runner.py", line 541, in _run_script
    exec(code, module.__dict__)
File "/app/main.py", line 271, in <module>
    page_names_to_funcs[demo_name]()
File "/app/forecast.py", line 202, in forecast_page
    if model != "cnn" and len(forecast) > 0 and show_prob:

This error doesn't occur with the cnn model