错误：生成ngr ENOENT

Question

我完全没有意识到这种错误， 什么导致这个错误怎么解决呢？

cross-env NODE_ENV=development ngr build dev

控制台错误。

events.js:165
      throw er; // Unhandled 'error' event
      ^

Error: spawn ngr ENOENT
    at Process.ChildProcess._handle.onexit (internal/child_process.js:201:19)
    at onErrorNT (internal/child_process.js:379:16)
    at process._tickCallback (internal/process/next_tick.js:114:19)
    at Function.Module.runMain (module.js:692:11)
    at startup (bootstrap_node.js:194:16)
    at bootstrap_node.js:666:3
Emitted 'error' event at:
    at Process.ChildProcess._handle.onexit (internal/child_process.js:207:12)
    at onErrorNT (internal/child_process.js:379:16)
    [... lines matching original stack trace ...]
    at bootstrap_node.js:666:3