Maybe your CSV is a bit off, for example, in a line one of the fields is empty or a separator is missing. Does it work if you use a copy of your CSV file containing only the first 10 lines (and where you can easily check if all lines look correct). At least you can tell if it’s a problem with the file, and not with torchtext.
For testing the CSV file, you could also try pandas. When loading a file pandas often gives more useful errors when something with the file is off. In case pandas throws indeed an error, you can also use it to clean your CVS:

Load your CSV file into a data frame with error_bad_lines=False to skip erroneous lines
Save data frame to a new CSV file which you that can feed to torchtext