Export not found on module

From https://devblogs.microsoft.com/typescript/announcing-typescript-3-8-beta/:

As a solution in TypeScript 3.8, we’ve added a new syntax for type-only imports and exports.

import type { SomeThing } from "./some-module.js";

export type { SomeThing };

Re-exporting types is one of the known TypeScript constructs that don't work when using Babel to compile TypeScript because they require cross-file information. You can enable the isolatedModules TypeScript compiler option to report these constructs as errors when you compile with tsc (not Babel) or use the TypeScript language service in an IDE. export * is one workaround; another described in this issue is to use a type alias instead of a re-export. Yet another workaround is to merge a constant with the interface. (It's a hack but avoids some of the disadvantages of the other approaches.)

export interface testInterface {
    name?: string;
}
export const testInterface = undefined;