Are you able to install Perl Modules? If so, install Text::CSV, and let me know when this is done.
There are two reasons that the Module may serve you well in this case. The first is that it's generally a best practice to use a Module that's built to handle csv files. In your case, the csv format wasn't complex, i.e., commas within quoted fields, so just splitting on commas was OK. However, thinking long-term, your data may get more complex, and Text::CSV would be able to handle it.
The second reason is based upon the error messages you shared. The variable $vars was uninitialized when it should have contained a value. This may be an issue of the csv file containing binary data, but I'm not sure. Text::CSV can handle this, too.
Let me know...