Fixed module type for production build

package.json

@@ -8,7 +8,7 @@
     "./lib/**/*"
   ],
   "scripts": {
-    "test:browser": "npm run build && cp ./src/__tests__/index.html ./lib/ && bash -c 'for module in \".\\/cache\" \".\\/types\" \".\\/utils\"; do sed -i \"s/$module/$module.js/g\" ./lib/index.js; done' && serve -s lib",
+    "test:browser": "npm run build -- --module 'esnext' && cp ./src/__tests__/index.html ./lib/ && bash -c 'for module in \".\\/cache\" \".\\/types\" \".\\/utils\"; do sed -i \"s/$module/$module.js/g\" ./lib/index.js; done' && serve -s lib",
     "build": "tsc",
     "test": "jest --config jestconfig.json --passWithNoTests",
     "prepare": "npm run build",

tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "target": "es5",
-    "module": "ESNext",
+    "module": "commonjs",
     "moduleResolution": "node",
     "declaration": true,
     "outDir": "./lib",