🧪 test: Allow CommonJS tests to run.

src/index.js

@@ -1,4 +1,7 @@
+export {IndexError} from '@failure-abstraction/error';
+
 export * as core from './core/index.js';
+
 export {default as heappop} from './heappop.js';
 export {default as heapify} from './heapify.js';
 export {default as heappushpop} from './heappushpop.js';

test/src/_fixtures.js

@@ -0,0 +1,3 @@
+import * as mod from '#module';
+
+export const {IndexError} = mod.default ?? mod;

test/src/heapq.js

@@ -1,9 +1,10 @@
 import test from 'ava';
 
-import {IndexError} from '@failure-abstraction/error';
 import {list} from '@iterable-iterator/list';
 import {increasing} from '@total-order/primitive';
 
+import {IndexError} from './_fixtures.js';
+
 import * as heapq from '#module';
 
 test('heapq', (t) => {