fix: gracefully handle unhandled promises

This prevents nuxt process exiting in dev mode on unhandled promises

bin/nuxt

@@ -1,5 +1,9 @@
 #!/usr/bin/env node
 
+// Node Source Map Support
+// https://github.com/evanw/node-source-map-support
+require('source-map-support').install()
+
 const join = require('path').join
 
 const defaultCommand = 'dev'
@@ -21,4 +25,11 @@ if (commands.has(cmd)) {
 
 const bin = join(__dirname, 'nuxt-' + cmd)
 
+// Console error unhandled promises
+process.on('unhandledRejection', function (err) {
+  /* eslint-disable no-console */
+  console.error(err)
+  console.error('[nuxt] Unhandled promise rejection: ' + err)
+})
+
 require(bin)

bin/nuxt-dev

@@ -54,11 +54,6 @@ const nuxtConfigFile = resolve(rootDir, argv['config-file'])
 const nuxtConfig = loadNuxtConfig()
 _.defaultsDeep(nuxtConfig, { watchers: { chokidar: { ignoreInitial: true } } })
 
-// Fail if an error happened
-process.on('unhandledRejection', function (err) {
-  throw err
-})
-
 // Start dev
 let dev = startDev()