Fix Improve "pages/ not found error" (#624)

* fix not found error

* add comment

bin/next-build

 #!/usr/bin/env node
 
-import { resolve } from 'path'
+import { resolve, join } from 'path'
+import { exists } from 'mz/fs'
 import parseArgs from 'minimist'
 import build from '../server/build'
 
@@ -27,6 +28,23 @@ if (argv.help) {
 
 const dir = resolve(argv._[0] || '.')
 
+// Check if pages dir exists and warn if not
+exists(dir)
+.then(async () => {
+  if (!(await exists(join(dir, 'pages')))) {
+    if (await exists(join(dir, '..', 'pages'))) {
+      console.error('> No `pages` directory found. Did you mean to run `next` in the parent (`../`) directory?')
+    } else {
+      console.error('> Couldn\'t find a `pages` directory. Please create one under the project root')
+    }
+    process.exit(1)
+  }
+})
+.catch((err) => {
+  console.error(err)
+  process.exit(1)
+})
+
 build(dir)
 .catch((err) => {
   console.error(err)

bin/next-dev

@@ -37,14 +37,9 @@ if (argv.help) {
 
 const dir = resolve(argv._[0] || '.')
 
-const srv = new Server({ dir, dev: true })
-srv.start(argv.port)
+// Check if pages dir exists and warn if not
+exists(dir)
 .then(async () => {
-  if (!process.env.NOW) {
-    console.log(`> Ready on http://localhost:${argv.port}`)
-  }
-
-  // Check if pages dir exists and warn if not
   if (!(await exists(join(dir, 'pages')))) {
     if (await exists(join(dir, '..', 'pages'))) {
       console.error('> No `pages` directory found. Did you mean to run `next` in the parent (`../`) directory?')
@@ -58,3 +53,15 @@ srv.start(argv.port)
   console.error(err)
   process.exit(1)
 })
+
+const srv = new Server({ dir, dev: true })
+srv.start(argv.port)
+.then(async () => {
+  if (!process.env.NOW) {
+    console.log(`> Ready on http://localhost:${argv.port}`)
+  }
+})
+.catch((err) => {
+  console.error(err)
+  process.exit(1)
+})