Error while getting file thumbnail is resolved

**Error Reference:**

Traceback (most recent call last):

  File "/home/glab/gstudio_metastudio/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 112, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)

  File "./gnowsys_ndf/ndf/views/file.py", line 973, in getFileThumbnail
    f = file_node.fs.files.get(ObjectId(file_node.fs_file_ids[1]))

IndexError: list index out of range