Importing complex types - NestJS tsconfig.json

Question

I am creating a full-stack application and I'm trying to standardize the communication between the front-end and the back-end. The back-end is being built using NestJS and Prisma.

Thus, I have created some complex Typescript types, trying to transform some of my data.

Specifically, I have a util.ts file outside the back-end's src folder (in order to share it) with below complex types:

/** Returns only non optional fields */
export type NoUndefined<T> = {
    [K in keyof T as T[K] extends Required<T>[K] ? K : never]: T[K]
}

/** Returns only nullable fields */
export type OnlyNull<T> = {
    [K in keyof T as T[K] extends Exclude<T[K], null> ? never : K]: T[K]
}

/** Returns only non optional and non null fields */
export type NoNullUndefined<T> = {
    [K in keyof T as T[K] extends Exclude<T[K], undefined | null> ? K : never]: T[K]
}

export type NoNullUndefined_NullToOptional<T> = NoNullUndefined<T> & Partial<NoUndefined<OnlyNull<T>>>

Let's say for example I have the object:

const before: {
    id: number,
    name: string,
    nullable_field: string | null,
    optional_field?: string
} = ...

The type of NoNullUndefined_NullToOptional<typeof before> will be

{
    id: number,
    name: string,
    nullable_field?: string | null,
}

When I am using said transformations in the same util.ts VSCode infers the type correctly. The same goes for when I'm importing them in the front-end project. That's awesome.

When I am importing the types and using them inside the NestJS project, though, VSCode infers the original (before, T) type. So even if I declare

const after: NoNullUndefined_NullToOptional<Users> = ...

VSCode and the NestJS compiler treat the object as a Users type and create errors.

I am guessing this is a tsconfig.json issue, but I don't know enough to figure out what's wrong.

I'm providing the back-end's tsconfig.json below:

{
  "compilerOptions": {
    "module": "commonjs",
    "declaration": true,
    "removeComments": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "allowSyntheticDefaultImports": true,
    "target": "es2017",
    "sourceMap": true,
    "outDir": "./dist",
    "baseUrl": "./",
    "incremental": true,
    "skipLibCheck": true,
    "strictNullChecks": false,
    "noImplicitAny": false,
    "strictBindCallApply": false,
    "forceConsistentCasingInFileNames": false,
    "noFallthroughCasesInSwitch": false,
    "paths": {
      "@models/*": [
        "../prisma/generated/*"
      ],
      "@sharedTypes/*": [
        "../shared/*"
      ]
    }
  }
}

Any ideas?