Problem converting RTF

When converting the attached book, got the following error:

calibre, version 0.9.15 (darwin, isfrozen: True)
Conversion Error: Failed: Convert book 1 of 1 (The Summa Theologica of St. Thomas Aquinas. Vol. 1)

Convert book 1 of 1 (The Summa Theologica of St. Thomas Aquinas. Vol. 1)
Resolved conversion options
calibre version: 0.9.15
{'asciiize': False,
 'author_sort': None,
 'authors': None,
 'base_font_size': 0.0,
 'book_producer': None,
 'change_justification': u'original',
 'chapter': u"//*[((name()='h1' or name()='h2') and re:test(., 'chapter|book|section|part|prologue|epilogue\\s+', 'i')) or @class = 'chapter']",
 'chapter_mark': u'pagebreak',
 'comments': None,
 'cover': None,
 'debug_pipeline': None,
 'dehyphenate': True,
 'delete_blank_paragraphs': True,
 'disable_font_rescaling': False,
 'dont_split_on_page_breaks': False,
 'duplicate_links_in_toc': False,
 'embed_font_family': None,
 'enable_heuristics': False,
 'epub_flatten': False,
 'extra_css': None,
 'extract_to': None,
 'filter_css': u'',
 'fix_indents': True,
 'flow_size': 260,
 'font_size_mapping': None,
 'format_scene_breaks': True,
 'html_unwrap_factor': 0.4,
 'input_encoding': None,
 'input_profile': <calibre.customize.profiles.InputProfile object at 0x108403bd0>,
 'insert_blank_line': False,
 'insert_blank_line_size': 0.5,
 'insert_metadata': False,
 'isbn': None,
 'italicize_common_cases': True,
 'keep_ligatures': False,
 'language': None,
 'level1_toc': None,
 'level2_toc': None,
 'level3_toc': None,
 'line_height': 0.0,
 'linearize_tables': False,
 'margin_bottom': 5.0,
 'margin_left': 5.0,
 'margin_right': 5.0,
 'margin_top': 5.0,
 'markup_chapter_headings': True,
 'max_toc_links': 50,
 'minimum_line_height': 120.0,
 'no_chapters_in_toc': False,
 'no_default_epub_cover': False,
 'no_inline_navbars': False,
 'no_svg_cover': False,
 'output_profile': <calibre.customize.profiles.OutputProfile object at 0x108403f90>,
 'page_breaks_before': u"//*[name()='h1' or name()='h2']",
 'prefer_metadata_cover': False,
 'preserve_cover_aspect_ratio': False,
 'pretty_print': True,
 'pubdate': None,
 'publisher': None,
 'rating': None,
 'read_metadata_from_opf': u'/var/folders/fn/cp1v7ltd44z64p0mnc15tk8r0000gn/T/calibre_0.9.15_tmp_TPO5yL/hUxT18.opf',
 'remove_fake_margins': True,
 'remove_first_image': False,
 'remove_paragraph_spacing': False,
 'remove_paragraph_spacing_indent_size': 1.5,
 'renumber_headings': True,
 'replace_scene_breaks': u'',
 'search_replace': '[]',
 'series': None,
 'series_index': None,
 'smarten_punctuation': False,
 'sr1_replace': None,
 'sr1_search': None,
 'sr2_replace': None,
 'sr2_search': None,
 'sr3_replace': None,
 'sr3_search': None,
 'start_reading_at': None,
 'subset_embedded_fonts': False,
 'tags': None,
 'timestamp': None,
 'title': None,
 'title_sort': None,
 'toc_filter': None,
 'toc_threshold': 6,
 'unsmarten_punctuation': False,
 'unwrap_lines': True,
 'use_auto_toc': False,
 'verbose': 2}
Python function terminated unexpectedly: list index out of range
InputFormatPlugin: RTF Input running
on /var/folders/fn/cp1v7ltd44z64p0mnc15tk8r0000gn/T/calibre_0.9.15_tmp_TPO5yL/RgEJam.rtf
Converting RTF to XML...
Traceback (most recent call last):
  File "/Applications/calibre.app/Contents/Resources/Python/lib/python2.7/site.py", line 147, in main
    return run_entry_point()
  File "/Applications/calibre.app/Contents/Resources/Python/lib/python2.7/site.py", line 116, in run_entry_point
    return getattr(pmod, func)()
  File "site-packages/calibre/utils/ipc/worker.py", line 186, in main
  File "site-packages/calibre/gui2/convert/gui_conversion.py", line 31, in gui_convert_override
  File "site-packages/calibre/gui2/convert/gui_conversion.py", line 25, in gui_convert
  File "site-packages/calibre/ebooks/conversion/plumber.py", line 1009, in run
  File "site-packages/calibre/customize/conversion.py", line 239, in __call__
  File "site-packages/calibre/ebooks/conversion/plugins/rtf_input.py", line 244, in convert
  File "site-packages/calibre/ebooks/conversion/plugins/rtf_input.py", line 103, in generate_xml
  File "site-packages/calibre/ebooks/rtf2xml/ParseRtf.py", line 213, in parse_rtf
  File "site-packages/calibre/ebooks/rtf2xml/tokenize.py", line 182, in tokenize
  File "site-packages/calibre/ebooks/rtf2xml/tokenize.py", line 55, in __unicode_process
IndexError: list index out of range