Fix some code quality issues and add code transformer

[siddhant-deepsource]

This pull request fixes some of the issues raised by DeepSource on my fork of this repo.

Some issues were automatically fixed by DeepSource, while I fixed some of them by hand.

This PR also contains a .deepsource.toml, in case you want to run continuous quality analyses on your repository. If you wish to do so, you can follow these steps:

• Merge this PR.
• Signup on DeepSource here.
• Activate analysis on your repo here.

Adding to reporting the code quality issues, I have also added the JavaScript (Prettier) Transformer which support auto-formatting of code on every new pull-request. You can find the transformers docs here.

If you don't want to use DeepSource, I can edit the PR to remove the .deepsource.toml file.

[siddhant-deepsource]

Hey @meganrm 👋 Just following up. It will be great if you can take a look once.

Thanks and a very Happy New Year 🙂