build error

[ErNisha4800]

Build the first setp
SUCCESS: msg\js\zh-hant.js
SUCCESS: blockly_uncompressed.js
Traceback (most recent call last):
self.run()
File "build.py", line 210, in gen_core
self.do_compile(params, target_filename, filenames, [])
File "build.py", line 280, in do_compile
json_data = json.loads(json_str)
File "c:\python27\lib\json_init_.py", line 339, in loads
return _default_decoder.decode(s)
File "c:\python27\lib\json\decoder.py", line 364, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File "c:\python27\lib\json\decoder.py", line 382, in raw_decode
raise ValueError("No JSON object could be decoded")
ValueError: No JSON object could be decoded