fix

package.json

@@ -6,6 +6,7 @@
   "license": "MIT",
   "main": "./dist/index.js",
   "types": "./dist/index.d.ts",
+  "type": "commonjs",
   "devDependencies": {
     "@babel/core": "^7.11.4",
     "@babel/preset-env": "^7.11.0",

tsconfig.json

@@ -4,7 +4,8 @@
     "target": "es2015",
     "declaration": true,
     "outDir": "./dist",
-    "allowJs": true
+    "allowJs": true,
+    "allowSyntheticDefaultImports": true
   },
   "include": ["src/**/*"]
 }