Emitting declarations for commonjs exported classes suggests classes are private, TS9006

[euclideansphere]

TypeScript Version: 4.0.3 (also happens in typescript@next)

private name,Declaration emit,block declaration emit,TS9006

a very simple code sample -
https://github.com/euclideansphere/private-declaration-issue

// utils/errors.js
class FancyError extends Error {
	constructor(status) {
		super(`error with status ${status}`);
	}
}

module.exports = {
	FancyError
}

// utils/index.js
// issue arises here on compilation
const errors = require("./errors");

module.exports = {
	errors
}

Expected behavior:

(master)⚡ % tsc # should run clean, exit with code 0

Actual behavior:

(master)⚡ % tsc                                                                                                                                                       ~/projects/private-declaration-issue
utils/index.js:1:1 - error TS9006: Declaration emit for this file requires using private name 'FancyError' from module '"/Users/austin/projects/private-declaration-issue/utils/errors"'. An explicit type annotation may unblock declaration emit.

1 const errors = require("./errors");
  ~~~~~


Found 1 error.

Playground Link:
https://github.com/euclideansphere/private-declaration-issue

Related Issues:
#9865 - seems to be an issue with "A inherits B but only A is exported", but in this case B is a global and adding it as an export doesn't resolve the issue.

[RyanCavanaugh]

Not 100% sure which behavior is right here