azure移动服务错误找不到模块'azure-storage'

I have been using Azure-storage npm module in my AzureMobileService custom API for past couple of months and all has been working fine, till couple of days back it started giving me this error - cannot find module 'azure-storage'. Its strange because I haven't changed my code a bit, actually the day it start giving me this error, I had checked my app(HTML/JS app) in the morning, it was all working good. But when I came back from work and ran the app, I got this error. below is the code in my custom api where I get this error npm module in m