Discussion on: You are reading environment variables the wrong way in Next.js

I don't really see the point of all this. You received a very common error with a simple to find cause and fixed it. Then you wrote a whole post about environment variables in which you overcomplicate the thing entirely.

Most developers that work with Next are expected to know some way to properly deal with environment variables with things like dotenv but let's assume they don't.

Why should a HTTP request to get a blog post know anything about the process environment?

Although poor choice of words, I know what you mean there and you are right. It makes sense to say that it shouldn't rely on process.env existing in that context. This is why we separate our application logic, especially with JavaScript. You can of course, write a fetchBlog function that takes one or more arguments.

Somewhere in your utils.js or something:

// with one argument like in your example
export const fetchBlog = apiKey => fetch(`https://www.example.com/api/blog?api_key=${apiKey}`)

// somewhere else where process.env is available and the logic is
import { fetchBlog } from './utils.js'
const { API_KEY } = process.env
fetchBlog(API_KEY).then(...)

Often there is not just an API key. With multiple arguments you can do something like this and pass an object.

// with multiple arguments
const fetchBlog = options => fetch(`https://www.example.com/api/blog?api_key=${options.apiKey}&post=${options.postId}`)

You can still insist on throwing exceptions simply inside the fetchBlog function.

// this function still has no idea what goes on in process.env
const fetchBlog = async options => {
    const { apiKey, postId } = options
    if(!apiKey) throw new Error(`Missing API key`)
    if(!postId) throw new Error(`Missing post id`)
    return fetch(`https://www.example.com/api/blog?api_key=${apiKey}&post=${postId}`)
}

Tadaa, no matter if apiKey or postId are undefined or the API endpoint itself returns an error because the key/post does not exist or some other reason, you receive proper feedback error message.

But even then, your post started with a typo case. It is useful to ask yourself if a real world situation exists where that could happen, especially if it is your own application. If your code design patterns and abstractions are correct then you will have dealt with the missing environment variable way before any HTTP request is made.

I think it is a bit early to tell people what will make them a better software engineer.