remove/change checks of whether files exist

[chunhochow]

Sections like

file_check = [WORKING_FOLDER, Nodes_File_Name] + transit_assignments
for path in file_check:
    if not os.path.exists(path):
        print(f"{path}: Not Exists")

Should these be just removed or be at least turned into raising an exception/warning

1. It's not even raising a Warning or Exception anyways, the script continues to run
2. The script would probably just fail later if files don't exist (and let you know that it failed because the file doesn't exist)... which should be fine. These scripts should not take so long that it would be a problem.