Why does d.ts files do not throw an error when importing inexistent variables/types?

Question

I've got a d.ts file that imports an inexistent variable/interface:

import { inexistentVariable } from './myFile.ts'
import { InexistentInterface } from './myTypes.d.ts'

In both cases, my IDEs (VSCode and WebStorm) do not warn me about this. I can actually make use of it with no warnings given:

interface A {
    b: InexistentInterface
}

When I hover b I get b: any.

This is my tsconfig:

{
  "target": "ES5",
  "module": "commonjs",
  "lib": [
    "esnext.asynciterable",
    "ES5",
    "ES6",
    "dom"
    ],
  "compilerOptions": {
    "skipLibCheck": true,
    "types": ["reflect-metadata", "jest", "jest-chain", "node"],
    "outDir": "dist",
    "strict": true, 
    "strictPropertyInitialization": false,  
    "esModuleInterop": true, 
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "forceConsistentCasingInFileNames": true,
    "moduleResolution": "node",
    "downlevelIteration": true,
    "baseUrl": ".",
  },
  "include": [
        "./"
    ],
  "exclude": [
        "node_modules"
    ]
}

Is there any way of getting an error when the imported feature does not exist in the codebase?

Answer 1

I believe this is intended behavior of Typescript to ensure cooperation with JavaScript. It was reported on the Typescript Github page here: Import path not checked when not importing any symbols #20534 and labeled "working as intended".

The example on github is a little different compared to what you posted, but the underlying reason for the behavior seems to be the same.