Updated "Unknown Error" copy

Author: pierrei

webpack_loader/loader.py

@@ -86,7 +86,7 @@ def get_bundle(self, bundle_name):
  if 'file' not in assets:
  assets['file'] = ''
  if 'error' not in assets:
- assets['error'] = 'error'
+ assets['error'] = 'Unknown Error'
  error = u"""
  {error} in {file}
  {message}