fix: add check before calling find on vue rule (#170)

lib/getVueRules.js

@@ -1,6 +1,3 @@
-
-const webpack = require('webpack')
-
 let vueLoaderPath
 try {
   vueLoaderPath = require.resolve('vue-loader')
@@ -18,9 +15,9 @@ module.exports = {
     const rules = compiler.options.module.rules
 
     // Naive approach without RuleSet or RuleSetCompiler
-    rules.map((rule, i) => rule.use && rule.use.find(isVueLoader) ? i : null).filter(v => v != null)
+    rules.map((rule, i) => rule.use && rule.use.find && rule.use.find(isVueLoader) ? i : null).filter(v => v != null)
 
     // find the rules that apply to vue files
-    return rules.filter(rule => rule.use && rule.use.find(isVueLoader))
+    return rules.filter(rule => rule.use && rule.use.find && rule.use.find(isVueLoader))
   }
 }