Uncaught SyntaxError: Cannot use import statement outside a module

Hi. I have attempted to add Buffer to my browser extension in the name of replacing the deprecated `btoa` method so that I may submit a pull request to Buildspace, whom have provided the extension's template. I have tried on multiple occasions in multiple ways to get the buffer to work but to no avail. The file in which I am trying to use buffer is the index.js at the root level of the app. Below I have attached screenshots and a link to my extension's repository so you can see the various changes I have made in attempting to get this to work. If you need any further info, please let me know. Thank you for your assistance.

https://github.com/SMSonGitHub/gpt3-writer-extension-sms

I have recently installed webpack and that seems to make the errors go away. I am currently testing the app, but it seems there may still be some issues. Any and all good help would be appreciated.