Ember Build error: Cannot find module '../functions/bind'

I'm working on an addon, that was up and running. Now, after a week not touching it I get that error when trying to serve/build:

module.js:339
throw err;
^
Error: Cannot find module '../functions/bind'
at Function.Module._resolveFilename (module.js:337:15)
at Function.Module._load (module.js:287:25)
at Module.require (module.js:366:17)
at require (module.js:385:17)
at Object. (C:....\node_modules\ember-cli\node_modules\core-object\node_modules\lodash-node\modern\internals\baseCreateCallback.js:9:12) at Module._compile (module.js:435:26)
at Object.Module._extensions..js (module.js:442:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:311:12)
at Module.require (module.js:366:17)
at require (module.js:385:17)

So I looked at baseCreateCallback.js Line 9:

var bind = require('../functions/bind'),

That makes me having a look to find that file.
I can find a ../functions/bindAll.js and ../functions/bindKey.js, but no 'bind.js'
So that error makes sense.
Only thing is, I have not updated ember-cli - at least not that I know of...

I disabled all essential code in my addon just to find out what I could have changed that produces this error. Also removed all imports that may cause this.

Now I wanted to tell you the version I am on (as far as I remember I lastly updated to 2.5), but also an ember -v gives me that same error. So basically my whole ember-cli installation is broken!?
(ember -v globally shows 2.5)

Does anybody have an idea why this could be?
(yes, I've searched Google and SO for similar cases.)