Error: Cannot find module 'string'

[ToeiRei]

2018-03-04T19:59:58.078Z [19337] - �[31merror�[39m: Error: Cannot find module 'string'
at Function.Module._resolveFilename (module.js:538:15)
at Function.Module._load (module.js:468:25)
at Module.require (module.js:587:17)
at Object. (/home/board/nodebb/node_modules/nodebb-plugin-telegram-notifications/library.js:13:20)
at Module._compile (module.js:643:30)
at Object.Module._extensions..js (module.js:654:10)
at Module.load (module.js:556:32)
at tryModuleLoad (module.js:499:12)
at Function.Module._load (module.js:491:3)
at Module.require (module.js:587:17)
at require (internal/module.js:11:18)
at Object.Plugins.requireLibrary (/home/board/nodebb/src/plugins.js:44:32)
at registerHooks (/home/board/nodebb/src/plugins/load.js:180:13)
at /home/board/nodebb/src/plugins/load.js:138:6
at /home/board/nodebb/node_modules/async/dist/async.js:3866:24
at eachOfArrayLike (/home/board/nodebb/node_modules/async/dist/async.js:1055:9)
2018-03-04T19:59:58.079Z [19337] - �[33mwarn�[39m: [plugins] Unable to parse library for: nodebb-plugin-telegram-notifications

[ToeiRei]

solution would be npm install string - not nice, but okay.