28 files changed, 150 insertions, 144 deletions

diff --git a/.electron-builder.config.js b/.electron-builder.config.cjs
index 5238c69..5238c69 100644
--- a/.electron-builder.config.js
+++ b/.electron-builder.config.cjs
diff --git a/config/build-common.js b/config/build-common.js
index aea2335..ff5a218 100644
--- a/config/build-common.js
+++ b/config/build-common.js
@@ -1,11 +1,17 @@
-// @ts-check
+import { readFileSync } from 'fs';
+import { dirname, join } from 'path';
+import { fileURLToPath } from 'url';
 
-// `resolveJsonModule` is disabled for this package, but vite will load the json nevertheless.
-// @ts-ignore
-const { chrome: chromeVersion, node: nodeVersion } = require('../.electron-vendors.cache.json');
+const thisDir = fileURLToDirname(import.meta.url);
+
+// We import this from a vite config, where top-level await is not available (es2021),
+// so we have to use the synchronous filesystem API.
+const electronVendorsJson = readFileSync(join(thisDir, '../.electron-vendors.cache.json'), 'utf8');
+
+const { chrome: chromeVersion, node: nodeVersion } = JSON.parse(electronVendorsJson);
 
 /** @type {string} */
-module.exports.banner = `/*!
+export const banner = `/*!
  * Copyright (C)  2021-2022 Sophie contributors
  *
  * This file is part of Sophie.
@@ -27,7 +33,15 @@ module.exports.banner = `/*!
 `;
 
 /** @type {string} */
-module.exports.chrome = `chrome${chromeVersion}`;
+export const chrome = `chrome${chromeVersion}`;
 
 /** @type {string} */
-module.exports.node = `node${nodeVersion}`;
+export const node = `node${nodeVersion}`;
+
+/**
+ * @param {string} url
+ * @returns {string}
+ */
+export function fileURLToDirname(url) {
+  return dirname(fileURLToPath(url));
+}
diff --git a/config/esbuild-config.js b/config/esbuild-config.js
index 9140b89..52d1a59 100644
--- a/config/esbuild-config.js
+++ b/config/esbuild-config.js
@@ -1,6 +1,4 @@
-// @ts-check
-
-const { banner } = require('./build-common');
+import { banner } from './build-common.js';
 
 /** @type {string} */
 const mode = process.env.MODE || 'development';
@@ -8,8 +6,10 @@ const mode = process.env.MODE || 'development';
 /** @type {boolean} */
 const isDevelopment = mode === 'development';
 
+/** @type {string} */
 const modeString = JSON.stringify(mode);
 
+/** @type {Record<string, string>} */
 const defineEnv = {
   'import.meta.env.DEV': JSON.stringify(isDevelopment),
   'import.meta.env.MODE': modeString,
@@ -20,13 +20,16 @@ const defineEnv = {
 
 /**
  * @param {import('esbuild').BuildOptions} config
- * @param {object | unknown} metaEnvVars
+ * @param {Record<string, string>} [metaEnvVars]
  * @returns {import('esbuild').BuildOptions}
  */
-module.exports.getConfig = function(config, metaEnvVars) {
+export function getConfig(config, metaEnvVars) {
+  /** @type {Record<string, string>} */
   const defineMeta = {};
-  for (const varName in metaEnvVars) {
-    defineMeta[`import.meta.env.${varName}`] = JSON.stringify(metaEnvVars[varName]);
+  if (metaEnvVars) {
+    for (const varName in metaEnvVars) {
+      defineMeta[`import.meta.env.${varName}`] = JSON.stringify(metaEnvVars[varName]);
+    }
   }
   return {
     logLevel: 'info',
diff --git a/jest.config.js b/jest.config.js
index eda029a..1aa0cbb 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -1,17 +1,21 @@
-// @ts-check
+import { join } from 'path';
 
-const { join } = require('path');
+import { fileURLToDirname } from './config/build-common.js';
+
+const dirname = fileURLToDirname(import.meta.url);
 
 /** @type {import('ts-jest').InitialOptionsTsJest} */
-module.exports = {
-  preset: 'ts-jest',
+export default {
+  preset: 'ts-jest/presets/default-esm',
   globals: {
     'ts-jest': {
       isolatedModules: true,
+      useESM: true,
     },
   },
   moduleNameMapper: {
-    '@sophie/(.+)': join(__dirname, 'packages/$1/src/index.ts'),
+    '@sophie/(.+)': join(dirname, 'packages/$1/src/index.ts'),
+    '^(\\.{1,2}/.*)\\.js$': '$1',
   },
   resetMocks: true,
   restoreMocks: true,
diff --git a/package.json b/package.json
index e30d6fd..620c9cc 100644
--- a/package.json
+++ b/package.json
@@ -13,6 +13,7 @@
   "engines": {
     "node": ">=v16.13"
   },
+  "type": "module",
   "main": "packages/main/dist/index.cjs",
   "scripts": {
     "clean": "rimraf dist packages/*/dist packages/*/tsconfig.tsbuildinfo .vite",
@@ -20,7 +21,7 @@
     "build": "node scripts/build.js",
     "precompile": "cross-env MODE=production yarn run build",
     "compile": "yarn precompile && yarn compile:electron-builder",
-    "compile:electron-builder": "electron-builder build --config .electron-builder.config.js --dir",
+    "compile:electron-builder": "electron-builder build --config .electron-builder.config.cjs --dir",
     "watch": "node scripts/watch.js",
     "typecheck": "yarn workspaces foreach -vpt run typecheck",
     "update-electron-vendors": "node scripts/update-electron-vendors.js",
diff --git a/packages/main/esbuild.config.js b/packages/main/esbuild.config.js
index 7653078..a39534d 100644
--- a/packages/main/esbuild.config.js
+++ b/packages/main/esbuild.config.js
@@ -1,7 +1,5 @@
-// @ts-check
-
-const { node } = require('../../config/build-common');
-const { getConfig } = require('../../config/esbuild-config');
+import { node, fileURLToDirname } from '../../config/build-common.js';
+import { getConfig } from '../../config/esbuild-config.js';
 
 const externalPackages = ['electron'];
 
@@ -9,8 +7,8 @@ if (process.env.MODE !== 'development') {
   externalPackages.push('electron-devtools-installer');
 }
 
-module.exports = getConfig({
-  absWorkingDir: __dirname,
+export default getConfig({
+  absWorkingDir: fileURLToDirname(import.meta.url),
   entryPoints: [
     'src/index.ts',
   ],
diff --git a/packages/main/package.json b/packages/main/package.json
index c118d2b..99451bd 100644
--- a/packages/main/package.json
+++ b/packages/main/package.json
@@ -2,7 +2,7 @@
   "name": "@sophie/main",
   "version": "0.1.0",
   "private": true,
-  "main": "dist/index.cjs",
+  "type": "module",
   "types": "dist-types/index.d.ts",
   "scripts": {
     "typecheck": "tsc"
diff --git a/packages/main/src/devTools.ts b/packages/main/src/devTools.ts
index 6c25b3e..7c7c86a 100644
--- a/packages/main/src/devTools.ts
+++ b/packages/main/src/devTools.ts
@@ -27,14 +27,12 @@ import type { BrowserWindow } from 'electron';
  * because the mobx-state-tree devtools are currently unmaintained.
  */
 export async function installDevToolsExtensions(): Promise<void> {
-  const installerPackage = await import('electron-devtools-installer');
+  // Hack to lazily require a CJS module from an ES module transpiled into a CJS module.
   const {
     default: installExtension,
     REACT_DEVELOPER_TOOLS,
     REDUX_DEVTOOLS,
-  } = installerPackage.default instanceof Function
-      ? installerPackage
-      : installerPackage.default as unknown as typeof import('electron-devtools-installer');
+  } = require('electron-devtools-installer');
   await installExtension(
     [
       REACT_DEVELOPER_TOOLS,
diff --git a/packages/preload/esbuild.config.js b/packages/preload/esbuild.config.js
index 76ac33f..de51fc5 100644
--- a/packages/preload/esbuild.config.js
+++ b/packages/preload/esbuild.config.js
@@ -1,10 +1,8 @@
-// @ts-check
+import { chrome, fileURLToDirname } from '../../config/build-common.js';
+import { getConfig } from '../../config/esbuild-config.js';
 
-const { chrome } = require('../../config/build-common');
-const { getConfig } = require('../../config/esbuild-config');
-
-module.exports = getConfig({
-  absWorkingDir: __dirname,
+export default getConfig({
+  absWorkingDir: fileURLToDirname(import.meta.url),
   entryPoints: [
     'src/index.ts',
   ],
diff --git a/packages/preload/jest.config.js b/packages/preload/jest.config.js
index 5334b14..faecf9a 100644
--- a/packages/preload/jest.config.js
+++ b/packages/preload/jest.config.js
@@ -1,9 +1,7 @@
-// @ts-check
-
-const rootConfig = require('../../jest.config.js');
+import rootConfig from '../../jest.config.js';
 
 /** @type {import('ts-jest').InitialOptionsTsJest} */
-module.exports = {
+export default {
   ...rootConfig,
   testEnvironment: 'jsdom',
 };
diff --git a/packages/preload/package.json b/packages/preload/package.json
index ac21618..e6dd0ee 100644
--- a/packages/preload/package.json
+++ b/packages/preload/package.json
@@ -3,10 +3,10 @@
   "version": "0.1.0",
   "private": true,
   "sideEffects": false,
-  "main": "dist/index.cjs",
+  "type": "module",
   "types": "dist-types/index.d.ts",
   "scripts": {
-    "test": "jest",
+    "test": "node --experimental-vm-modules ../../node_modules/jest/bin/jest.js",
     "typecheck": "tsc"
   },
   "dependencies": {
diff --git a/packages/preload/src/__mocks__/electron.ts b/packages/preload/src/__mocks__/electron.ts
deleted file mode 100644
index 52cddf9..0000000
--- a/packages/preload/src/__mocks__/electron.ts
+++ /dev/null
@@ -1,25 +0,0 @@
-/*
- * Copyright (C)  2021-2022 Kristóf Marussy <kristof@marussy.com>
- *
- * This file is part of Sophie.
- *
- * Sophie is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License as
- * published by the Free Software Foundation, version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-export const ipcRenderer = {
-  invoke: jest.fn(),
-  on: jest.fn(),
-  send: jest.fn(),
-};
diff --git a/packages/preload/src/contextBridge/__tests__/SophieRendererImpl.spec.ts b/packages/preload/src/contextBridge/__tests__/SophieRendererImpl.spec.ts
index 71ac2a1..e40dcf5 100644
--- a/packages/preload/src/contextBridge/__tests__/SophieRendererImpl.spec.ts
+++ b/packages/preload/src/contextBridge/__tests__/SophieRendererImpl.spec.ts
@@ -18,8 +18,8 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
+import { describe, it, jest } from '@jest/globals';
 import { mocked } from 'jest-mock';
-import { ipcRenderer } from 'electron';
 import type { IJsonPatch } from 'mobx-state-tree';
 import {
   Action,
@@ -29,9 +29,17 @@ import {
   SophieRenderer,
 } from '@sophie/shared';
 
-import { createSophieRenderer } from '../SophieRendererImpl';
+jest.unstable_mockModule('electron', () => ({
+  ipcRenderer: {
+    invoke: jest.fn(),
+    on: jest.fn(),
+    send: jest.fn(),
+  },
+}));
 
-jest.mock('electron');
+const { ipcRenderer } = await import('electron');
+
+const { createSophieRenderer } = await import('../SophieRendererImpl');
 
 const event: Electron.IpcRendererEvent = null as unknown as Electron.IpcRendererEvent;
 
diff --git a/packages/preload/tsconfig.json b/packages/preload/tsconfig.json
index 741d435..0f27305 100644
--- a/packages/preload/tsconfig.json
+++ b/packages/preload/tsconfig.json
@@ -6,9 +6,6 @@
       "dom",
       "dom.iterable",
       "esnext"
-    ],
-    "types": [
-      "@types/jest"
     ]
   },
   "references": [
diff --git a/packages/renderer/package.json b/packages/renderer/package.json
index fb13129..2a26b2b 100644
--- a/packages/renderer/package.json
+++ b/packages/renderer/package.json
@@ -2,7 +2,7 @@
   "name": "@sophie/renderer",
   "version": "0.1.0",
   "private": true,
-  "main": "dist/index.html",
+  "type": "module",
   "types": "dist-types/index.d.ts",
   "scripts": {
     "typecheck": "tsc"
diff --git a/packages/renderer/vite.config.js b/packages/renderer/vite.config.js
index 30729c0..6f3d351 100644
--- a/packages/renderer/vite.config.js
+++ b/packages/renderer/vite.config.js
@@ -1,12 +1,12 @@
-// @ts-check
-
 /* eslint-env node */
 
 import { builtinModules } from 'module';
 import { join } from 'path';
 import react from '@vitejs/plugin-react';
 
-import { banner, chrome } from '../../config/build-common';
+import { banner, chrome, fileURLToDirname } from '../../config/build-common.js';
+
+const thisDir = fileURLToDirname(import.meta.url);
 
 const mode = process.env.MODE || 'development';
 
@@ -20,8 +20,8 @@ export default {
   /** @type {import('vite').LogLevel} */
   logLevel: 'info',
   mode,
-  root: __dirname,
-  cacheDir: join(__dirname, '../../.vite'),
+  root: thisDir,
+  cacheDir: join(thisDir, '../../.vite'),
   plugins: [
     react({
       babel: {
diff --git a/packages/service-inject/esbuild.config.js b/packages/service-inject/esbuild.config.js
index 38e5b7d..3f1d6d0 100644
--- a/packages/service-inject/esbuild.config.js
+++ b/packages/service-inject/esbuild.config.js
@@ -1,10 +1,8 @@
-// @ts-check
+import { chrome, fileURLToDirname } from '../../config/build-common.js';
+import { getConfig } from '../../config/esbuild-config.js';
 
-const { chrome } = require('../../config/build-common');
-const { getConfig } = require('../../config/esbuild-config');
-
-module.exports = getConfig({
-  absWorkingDir: __dirname,
+export default getConfig({
+  absWorkingDir: fileURLToDirname(import.meta.url),
   entryPoints: [
     'src/index.ts',
   ],
diff --git a/packages/service-inject/package.json b/packages/service-inject/package.json
index 825de24..7c496fd 100644
--- a/packages/service-inject/package.json
+++ b/packages/service-inject/package.json
@@ -3,7 +3,7 @@
   "version": "0.1.0",
   "private": true,
   "sideEffects": false,
-  "main": "dist/index.cjs",
+  "type": "module",
   "types": "dist-types/index.d.ts",
   "scripts": {
     "typecheck": "tsc"
diff --git a/packages/service-preload/esbuild.config.js b/packages/service-preload/esbuild.config.js
index 76ac33f..3c67b31 100644
--- a/packages/service-preload/esbuild.config.js
+++ b/packages/service-preload/esbuild.config.js
@@ -1,10 +1,8 @@
-// @ts-check
+import { chrome, fileURLToDirname } from "../../config/build-common.js";
+import { getConfig } from '../../config/esbuild-config.js';
 
-const { chrome } = require('../../config/build-common');
-const { getConfig } = require('../../config/esbuild-config');
-
-module.exports = getConfig({
-  absWorkingDir: __dirname,
+export default getConfig({
+  absWorkingDir: fileURLToDirname(import.meta.url),
   entryPoints: [
     'src/index.ts',
   ],
diff --git a/packages/service-preload/package.json b/packages/service-preload/package.json
index 7cbdfc8..8da5eb7 100644
--- a/packages/service-preload/package.json
+++ b/packages/service-preload/package.json
@@ -2,7 +2,7 @@
   "name": "@sophie/service-preload",
   "version": "0.1.0",
   "private": true,
-  "main": "dist/index.js",
+  "type": "module",
   "types": "dist-types/index.d.ts",
   "scripts": {
     "typecheck": "tsc"
diff --git a/packages/service-shared/esbuild.config.js b/packages/service-shared/esbuild.config.js
index ce57cd7..8df2edf 100644
--- a/packages/service-shared/esbuild.config.js
+++ b/packages/service-shared/esbuild.config.js
@@ -1,10 +1,8 @@
-// @ts-check
+import { chrome, fileURLToDirname } from '../../config/build-common.js';
+import { getConfig } from '../../config/esbuild-config.js';
 
-const { chrome } = require('../../config/build-common');
-const { getConfig } = require('../../config/esbuild-config');
-
-module.exports = getConfig({
-  absWorkingDir: __dirname,
+export default getConfig({
+  absWorkingDir: fileURLToDirname(import.meta.url),
   entryPoints: [
     'src/index.ts',
   ],
diff --git a/packages/service-shared/package.json b/packages/service-shared/package.json
index e812e4a..5c8ea79 100644
--- a/packages/service-shared/package.json
+++ b/packages/service-shared/package.json
@@ -3,7 +3,8 @@
   "version": "0.1.0",
   "private": true,
   "sideEffects": false,
-  "module": "dist/index.mjs",
+  "type": "module",
+  "main": "dist/index.mjs",
   "types": "dist/index.d.ts",
   "scripts": {
     "typecheck": "tsc"
diff --git a/packages/shared/esbuild.config.js b/packages/shared/esbuild.config.js
index f58d776..fbaa6f1 100644
--- a/packages/shared/esbuild.config.js
+++ b/packages/shared/esbuild.config.js
@@ -1,10 +1,8 @@
-// @ts-check
+import { chrome, fileURLToDirname } from '../../config/build-common.js';
+import { getConfig } from '../../config/esbuild-config.js';
 
-const { chrome } = require('../../config/build-common');
-const { getConfig } = require('../../config/esbuild-config');
-
-module.exports = getConfig({
-  absWorkingDir: __dirname,
+export default getConfig({
+  absWorkingDir: fileURLToDirname(import.meta.url),
   entryPoints: [
     'src/index.ts',
   ],
diff --git a/packages/shared/package.json b/packages/shared/package.json
index e4b57b0..428bff3 100644
--- a/packages/shared/package.json
+++ b/packages/shared/package.json
@@ -3,7 +3,8 @@
   "version": "0.1.0",
   "private": true,
   "sideEffects": false,
-  "module": "dist/index.mjs",
+  "type": "module",
+  "main": "dist/index.mjs",
   "types": "dist/index.d.ts",
   "scripts": {
     "typecheck": "tsc"
diff --git a/scripts/build.js b/scripts/build.js
index 5abcdab..9b9b26e 100644
--- a/scripts/build.js
+++ b/scripts/build.js
@@ -1,19 +1,28 @@
-const esbuild = require('esbuild');
-const { join } = require('path');
-const vite = require('vite');
+import { build as esbuildBuild } from 'esbuild';
+import { join } from 'path';
+import { build as viteBuild } from 'vite';
+
+import { fileURLToDirname } from '../config/build-common.js';
+
+const thisDir = fileURLToDirname(import.meta.url);
 
 /**
  * @param {string} packageName
  * @returns {Promise<import('esbuild').BuildResult>}
  */
-function buildPackageEsbuild(packageName) {
-  const config = require(`../packages/${packageName}/esbuild.config.js`);
-  return esbuild.build(config);
+async function buildPackageEsbuild(packageName) {
+  /** @type {{ default: import('esbuild').BuildOptions }} */
+  const { default: config } = await import(`../packages/${packageName}/esbuild.config.js`);
+  return esbuildBuild(config);
 }
 
+/**
+ * @param {string} packageName
+ * @returns {Promise<unknown>}
+ */
 function buildPackageVite(packageName) {
-  return vite.build({
-    configFile: join(__dirname, `../packages/${packageName}/vite.config.js`),
+  return viteBuild({
+    configFile: join(thisDir, `../packages/${packageName}/vite.config.js`),
   });
 }
 
diff --git a/scripts/update-electron-vendors.js b/scripts/update-electron-vendors.js
index 650d394..fea8b9d 100644
--- a/scripts/update-electron-vendors.js
+++ b/scripts/update-electron-vendors.js
@@ -1,11 +1,9 @@
-#!/usr/bin/env node
+import { execSync } from 'child_process';
+import electronPath from 'electron';
+import { writeFile } from 'fs/promises';
+import { join, resolve } from 'path';
 
-// @ts-check
-
-const { execSync } = require('child_process');
-const electronPath = require('electron');
-const { writeFile } = require('fs/promises');
-const path = require('path');
+import { fileURLToDirname } from '../config/build-common.js';
 
 /**
  * Returns versions of electron vendors
@@ -34,11 +32,11 @@ function updateVendors() {
   const nodeMajorVersion = electronRelease.node.split('.')[0];
   const chromeMajorVersion = electronRelease.v8.split('.')[0] + electronRelease.v8.split('.')[1];
 
-  const browserslistrcPath = path.resolve(process.cwd(), '.browserslistrc');
+  const browserslistrcPath = resolve(process.cwd(), '.browserslistrc');
 
   return Promise.all([
     writeFile(
-      './.electron-vendors.cache.json',
+      join(fileURLToDirname(import.meta.url), '../.electron-vendors.cache.json'),
       JSON.stringify({
         chrome: chromeMajorVersion,
         node: nodeMajorVersion,
diff --git a/scripts/watch.js b/scripts/watch.js
index d4229e9..82a8feb 100644
--- a/scripts/watch.js
+++ b/scripts/watch.js
@@ -1,20 +1,20 @@
-// @ts-check
+import { build as esbuildBuild } from 'esbuild';
+import { spawn } from 'child_process';
+import { watch } from 'chokidar';
+import electronPath from 'electron';
+import { join } from 'path';
+import { createServer } from 'vite';
 
-const esbuild = require('esbuild');
-const { spawn } = require('child_process');
-const chokidar = require('chokidar');
-const electronPath = require('electron');
-const { join } = require('path');
-const { createServer } = require('vite');
+import { fileURLToDirname } from '../config/build-common.js';
 
-process.env.MODE = 'development';
-process.env.NODE_ENV = 'development';
+/** @type {string} */
+const thisDir = fileURLToDirname(import.meta.url);
 
 /** @type {string} */
-const sharedModule = join(__dirname, '../packages/shared/dist/index.mjs');
+const sharedModule = join(thisDir, '../packages/shared/dist/index.mjs');
 
 /** @type {string} */
-const serviceSharedModule = join(__dirname, '../packages/service-shared/dist/index.mjs');
+const serviceSharedModule = join(thisDir, '../packages/service-shared/dist/index.mjs');
 
 /** @type {RegExp[]} */
 const stderrIgnorePatterns = [
@@ -34,15 +34,17 @@ const stderrIgnorePatterns = [
  * @return {Promise<void>}
  */
 async function setupEsbuildWatcher(packageName, extraPaths, callback) {
-  const config = require(`../packages/${packageName}/esbuild.config.js`);
+  /** @type {{ default: import('esbuild').BuildOptions }} */
+  const { default: config } = await import(`../packages/${packageName}/esbuild.config.js`);
   config.logLevel = 'info';
   config.incremental = true;
-  const incrementalBuild = await esbuild.build(config);
+
+  const incrementalBuild = await esbuildBuild(config);
   const paths = [
-    join(__dirname, `../packages/${packageName}/src`),
+    join(thisDir, `../packages/${packageName}/src`),
     ...(extraPaths || []),
   ];
-  const watcher = chokidar.watch(paths, {
+  const watcher = watch(paths, {
     ignored: /(^|[\/\\])\.|__(tests|mocks)__|\.(spec|test)\.[jt]sx?$/,
     ignoreInitial: true,
     persistent: true,
@@ -51,7 +53,7 @@ async function setupEsbuildWatcher(packageName, extraPaths, callback) {
     callback();
   }
   watcher.on('change', () => {
-    incrementalBuild.rebuild().then(() => {
+    incrementalBuild.rebuild?.().then(() => {
       if (callback) {
         console.log(`\u26a1 Reloading package ${packageName}`);
         callback();
@@ -81,7 +83,7 @@ async function setupDevServer(packageName) {
         clearScreen: false,
       },
     },
-    configFile: join(__dirname, `../packages/${packageName}/vite.config.js`),
+    configFile: join(thisDir, `../packages/${packageName}/vite.config.js`),
   });
   await viteDevServer.listen();
   return viteDevServer;
@@ -158,6 +160,9 @@ function setupMainPackageWatcher(viteDevServer) {
  * @returns {Promise<void>}
  */
 async function setupDevEnvironment() {
+  process.env.MODE = 'development';
+  process.env.NODE_ENV = 'development';
+
   /** @type {import('vite').ViteDevServer | null} */
   let viteDevServer = null;
   /** @type {(event: import('vite').HMRPayload) => void} */
@@ -182,6 +187,11 @@ async function setupDevEnvironment() {
     ])),
   ]);
 
+  if (viteDevServer === null) {
+    console.error('Failed to create vite dev server');
+    return;
+  }
+
   console.log('\ud83c\udf80 Sophie is starting up')
   return setupMainPackageWatcher(viteDevServer);
 }
diff --git a/tsconfig.json b/tsconfig.json
index 270616b..dfffc9d 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
-    "module": "esnext",
-    "target": "esnext",
+    "module": "es2022",
+    "target": "es2021",
     "moduleResolution": "node",
     "esModuleInterop": true,
     "allowSyntheticDefaultImports": true,
@@ -11,6 +11,7 @@
     "exactOptionalPropertyTypes": true,
     "isolatedModules": true,
     "skipLibCheck": true,
+    "checkJs": true,
     "lib": [
       "esnext"
     ]