See this issue in the Light Table issue tracker: https://github.com/LightTable/Python/issues/16
One solution recommended there:
- Open C:\Program Files\LightTable\plugins\python\python_compiled.js
- On line 96 replace
lt.plugins.python.escape_spaces.call(null,lt.plugins.python.py_path)
withlt.plugins.python.py_path
- Save file and restart Light Table
Credit to GitHub user gpiancastelli for finding this solution.