How can i solve this?

Hi everybody. I am new programming in this framework and basically in React. I want to make an extension that in first instance returns me the text that I select with the mouse and shows it on the screen but as attached in the screenshot it doesn't work correctly. I copy the repository because I really don't know what I have wrong, could someone know how to solve it? Repository: Thank you very much in advance
GitHub - pablo2899/Plasmo-framework
Contribute to pablo2899/Plasmo-framework development by creating an account on GitHub.
No description