Objection 2.1.5
Typescript 3.9.3

Issue:
When using mixins in Typescript the compiler gets confused about the 'Knex' type, throwing the following error: Return type of exported function has or is using name 'Knex' from external module [...] but cannot be named.ts(4058)

How to reproduce

import { Model } from 'objection';

export function Mixin(options = {}) {
  return function<T extends typeof Model>(Base: T) {
    return class extends Base {
      mixinMethod() {}
    };
  };
}

Taking the Mixing example from the homepage, dropping it into a fresh project. (Note: the example appears to have other issues, at least in TS 3.9.3, but those I can solve... the Knex error however won't go away no matter what I do.) For all other purposes, typings appear to work, however.

Experimenting a little with Objections typings I could solve the issue by replacing:

import * as knex from 'knex';
import Knex = require('knex');

in index.d.ts with:

import knex from 'knex'

In my project that solved the issue with the Knex error without adding any others... but it is a little weird. Though I guess the second import is a strange combo of commonJS and ES Modules... so that may throw the compiler?

Further Info
Some background to the issue: microsoft/TypeScript#5711