fix($core): Generated js have SyntaxError when source-map is enabled (close: #1367) (#1378)

packages/@vuepress/core/lib/build.js

@@ -47,7 +47,13 @@ module.exports = async function build (sourceDir, cliOptions = {}) {
   // find and remove empty style chunk caused by
   // https://github.com/webpack-contrib/mini-css-extract-plugin/issues/85
   // TODO remove when it's fixed
-  await workaroundEmptyStyleChunk()
+  if (!clientConfig.devtool && (!clientConfig.plugins ||           
+    !clientConfig.plugins.some(p =>
+      p instanceof webpack.SourceMapDevToolPlugin ||
+      p instanceof webpack.EvalSourceMapDevToolPlugin
+    ))) {
+    await workaroundEmptyStyleChunk()
+  }
 
   // create server renderer using built manifests
   const renderer = createBundleRenderer(serverBundle, {

yarn.lock

@@ -6568,7 +6568,7 @@ markdown-it-anchor@^5.0.2:
 
 markdown-it-chain@^1.3.0:
   version "1.3.0"
-  resolved "http://registry.npm.taobao.org/markdown-it-chain/download/markdown-it-chain-1.3.0.tgz#ccf6fe86c10266bafb4e547380dfd7f277cc17bc"
+  resolved "https://registry.yarnpkg.com/markdown-it-chain/-/markdown-it-chain-1.3.0.tgz#ccf6fe86c10266bafb4e547380dfd7f277cc17bc"
   dependencies:
     webpack-chain "^4.9.0"