I am trying to build **XTK** following [this link](https://github.com/xtk/X/wiki/X:DevelopersHeadsUp) on Linux running on Oracle VirtualBox to get non-minified `xtk.js`. I am getting following error when I tried to generate the `xtk-deps.js` on running `deps.py` file: 

```
Generating dependency file for XTK...
Traceback (most recent call last):
File "/root/Downloads/X-master/lib/google-closure-library/closure/bin/build/depswriter.py", line 212, in <module>
main()
File "/root/Downloads/X-master/lib/google-closure-library/closure/bin/build/depswriter.py", line 196, in main
path_to_source[depspath] = source.Source(source.GetFileContents(srcpath))
File "/root/Downloads/X-master/lib/google-closure-library/closure/bin/build/source.py", line 126, in GetFileContents
return fileobj.read()
File "/usr/lib/python2.7/codecs.py", line 668, in read
return self.reader.read(size)
File "/usr/lib/python2.7/codecs.py", line 474, in read
newchars, decodedbytes = self.decode(data, self.errors)
File "/usr/lib/python2.7/encodings/utf_8_sig.py", line 104, in decode
return codecs.utf_8_decode(input, errors)
UnicodeDecodeError: 'utf8' codec can't decode byte 0x9a in position 4584: invalid start byte
Could not generate dependency file.  

```

Could anybody please explain why this error is coming.