Add node trace source map handling in dev mode (vercel#2816)

* Add node trace source map handling in dev mode

Fixes vercel#2285

* Fix typo in comment

Author: kpdecker

server/build/webpack.js

@@ -247,8 +247,23 @@ export default async function createCompiler (dir, { dev = false, quiet = false,
           inputSourceMap: sourceMap
         })
 
+        // Strip ?entry to map back to filesystem and work with iTerm, etc.
+        let { map } = transpiled
+        let output = transpiled.code
+
+        if (map) {
+          map.sources = map.sources.map((source) => source.replace(/\?entry/, ''))
+          delete map.sourcesContent
+
+          // Output explicit inline source map that source-map-support can pickup via requireHook mode.
+          // Since these are not formal chunks, the devtool infrastructure in webpack does not output
+          // a source map for these files.
+          const sourceMapUrl = new Buffer(JSON.stringify(map), 'utf-8').toString('base64')
+          output = `${output}\n//# sourceMappingURL=data:application/json;charset=utf-8;base64,${sourceMapUrl}`
+        }
+
         return {
-          content: transpiled.code,
+          content: output,
           sourceMap: transpiled.map
         }
       }

server/index.js

@@ -29,6 +29,14 @@ const blockedPages = {
 
 export default class Server {
   constructor ({ dir = '.', dev = false, staticMarkup = false, quiet = false, conf = null } = {}) {
+    // When in dev mode, remap the inline source maps that we generate within the webpack portion
+    // of the build.
+    if (dev) {
+      require('source-map-support').install({
+        hookRequire: true
+      })
+    }
+
     this.dir = resolve(dir)
     this.dev = dev
     this.quiet = quiet