istanbul export const coverage repro

file.mjs

export const num = 1;

repro.sh

npx nyc -a -n file.mjs -r text -c false node --test test.mjs

test.mjs

import {num} from './file.mjs';
import assert from 'node:assert';
import {describe, it} from 'node:test';

describe('num', function() {
  it('should be 1', function() {
    assert.equal(num, 1);
  });
});