fix: [plugin] Use compiler.webpack when possible (#1822)

fixes #1781

Author: artagnon

lib/plugin-webpack5.js

@@ -31,9 +31,10 @@ const ruleSetCompiler = new RuleSetCompiler([
 
 class VueLoaderPlugin {
   apply (compiler) {
+    const normalModule = compiler.webpack.NormalModule || require("webpack/lib/NormalModule")
     // add NS marker so that the loader can detect and report missing plugin
     compiler.hooks.compilation.tap(id, compilation => {
-      const normalModuleLoader = require('webpack/lib/NormalModule').getCompilationHooks(compilation).loader
+      const normalModuleLoader = normalModule.getCompilationHooks(compilation).loader
       normalModuleLoader.tap(id, loaderContext => {
         loaderContext[NS] = true
       })