Feature flags VUE_OPTIONS_API, VUE_PROD_DEVTOOLS are not explicitly defined. You are running the esm-bundler build of Vue, which expects these compile-time feature flags to be globally injected via the bundler config in order to get better tree-shaking in the production bundle.
plugins: [
new webpack.DefinePlugin({
__VUE_OPTIONS_API__: false,
__VUE_PROD_DEVTOOLS__: false,
}),
],