Sounds like you are trying to run that js file but it's not made to be run.
Post where you got the instructions to do this migration.
I'm sorry, I should have come back here last week to post that I had decided against that process & just forwarded a couple emails that I needed to keep, then Uninstalled Thunderbird since I don't care for it anyway.
Thank you for the reply tho'.
This thread can be closed or whatever this board does.