npm and error messages

node_modules/vue/src/server/util.js

@@ -0,0 +1,18 @@
+/* @flow */
+
+export const isJS = (file: string): boolean => /\.js(\?[^.]+)?$/.test(file)
+
+export const isCSS = (file: string): boolean => /\.css(\?[^.]+)?$/.test(file)
+
+export function createPromiseCallback () {
+  let resolve, reject
+  const promise: Promise<string> = new Promise((_resolve, _reject) => {
+    resolve = _resolve
+    reject = _reject
+  })
+  const cb = (err: Error, res?: string) => {
+    if (err) return reject(err)
+    resolve(res || '')
+  }
+  return { promise, cb }
+}