lib: temporary workaround as terser v3.16 is buggy (vuejs/vue-cli#3407 (comment))

Author: peterpeterparker

package-lock.json

@@ -29,6 +29,7 @@
     "lite-server": "^2.4.0",
     "progress-bar-webpack-plugin": "^1.11.0",
     "style-loader": "^0.23.1",
+    "terser": "^3.14.1",
     "webpack": "^4.28.4",
     "webpack-cli": "^3.2.1",
     "workbox-webpack-plugin": "^3.6.3"