fix: clone babelLoader to use dynamicImport plugin

packages/webpack-uni-mp-loader/lib/script-new.js

@@ -125,12 +125,21 @@ module.exports = function (content, map) {
       usingComponents[name] = `/${source}`
     })
 
-    const babelLoader = findBabelLoader(this.loaders)
+    let babelLoader = findBabelLoader(this.loaders)
     if (!babelLoader) {
       callback(new Error(uniI18n.__('mpLoader.findFail', {
         0: 'babel-loader'
       })), content)
     } else {
+      const webpack = require('webpack')
+      if (webpack.version[0] > 4) {
+        // clone babelLoader and options
+        const index = this.loaders.indexOf(babelLoader)
+        const newBabelLoader = Object.assign({}, babelLoader)
+        Object.assign(newBabelLoader, { options: Object.assign({}, babelLoader.options) })
+        this.loaders.splice(index, 1, newBabelLoader)
+        babelLoader = newBabelLoader
+      }
       addDynamicImport(babelLoader, resourcePath, dynamicImports)
 
       updateUsingComponents(resourcePath, usingComponents, type)
@@ -139,4 +148,4 @@ module.exports = function (content, map) {
   }, err => {
     callback(err, content, map)
   })
-}
+}