fix(bridge): set webpack as implicit external

Author: pi0

build.config.ts

@@ -3,5 +3,8 @@ import { defineBuildConfig } from 'unbuild'
 export default defineBuildConfig({
   entries: [
     'src/module'
+  ],
+  externals: [
+    'webpack'
   ]
 })

src/async-loading.ts

@@ -1,6 +1,6 @@
 // Based on https://github.com/webpack/webpack/blob/v4.46.0/lib/node/NodeMainTemplatePlugin.js#L81-L191
 
-import { Compiler } from 'webpack'
+import type { Compiler } from 'webpack'
 import Template from 'webpack/lib/Template'
 
 export class AsyncLoadingPlugin {