Better errors

[ThatXliner]

• [ ] Better error message displays in app (using the toast)
• [ ] Error page styling (e.g. 404 page)
• [ ] Potentially add analytics (hopefully not necessary though)
• [x] Maybe some indication of our GitHub repository?

[ThatXliner]

Also, Next.js form validation https://github.com/vercel/next.js/blob/1f798f46472de29ea9e47b0d15b8341ece884033/examples/next-forms/app/add-form.tsx#L22

[ThatXliner]

Remember to go through all code paths (e.g. missing codes). Additionally, add tests