I'm submitting a bug report

Webpack Version:
4.x

Babel Core Version:
7.x

Babel Loader Version:
8.0.x

Please tell us about your environment:
OSX 10.x

Current behavior:
babel-loader is unable to resolve d.ts files when:

they're re-exported from a file
and that file also exports variables
and those variables are imported AND read in another file

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem along with a gist/jsbin of your webpack configuration.

I created a repo to illustrate this issue: https://github.com/bpander/babel-loader-issue

1. Create a file (File A) that re-exports some typescript types (e.g. export * from './types/Something') as well as variables (e.g. export const foo = 'bar').
2. In another file (File B), import * from File A.
3. Observe babel-loader has no issues building.
4. In File B, read a variable from the import (e.g. with console.log).
5. Observe babel-loader cannot resolve the re-exported types.

For example:

// FileA.ts
export * from './types/Something';
export const foo = 'bar';

// FileB.ts
import * as lib from './FileA';

const s: lib.Something = { k: 'v' };
console.log(s);

// Commenting out next line will "fix" babel-loader
console.log(lib.foo);

The above code results in the following error when compiled with babel-loader, but not babel or tsc.

ERROR in ./src/lib/index.ts
Module not found: Error: Can't resolve './types/Something' in '/Users/home/Code/babel-loader-issue/src/lib'
 @ ./src/lib/index.ts 1:0-34 1:0-34
 @ ./src/index.ts

What is the expected behavior?
babel-loader matches the behavior of babel and typescript and is able to resolve the file.

What is the motivation / use case for changing the behavior?
If something compiles in both typescript and babel, it stands to reason it should compile in babel-loader too.

Possibly irrelevant postscript
This is similar to #603, but I believe this is a distinct issue and one with babel-loader because:

a) in my reduced test case (https://github.com/bpander/babel-loader-issue), I set isolatedModules to true, and typescript still has no issues compiling
b) babel-loader doesn't complain unless you read a variable from the import