elasticsearch.helpers.errors.BulkIndexError: ('9 document(s) failed to index.', [
  {'index':
    {'_index': 'toolhub_lists',
     '_type': 'doc',
     '_id': '4',
     'status': 400,
     'error': {
       'type': 'mapper_parsing_exception',
       'reason': 'failed to parse',
       'caused_by': {
         'type': 'illegal_state_exception',
         'reason': "Can't handle serializing a dynamic type with content token [VALUE_NULL] and field name [x_merged_type]"
       }
     }
     'data': {
       'tools': [
         {
           'name': 'toolforge-anticompositetools-hyphenator',
           'title': 'Hyphenator',
           'description': 'Adds hyphens to ISBNs and converts 10-digit ISBNs to 13-digit ISBNs.',
           'url': 'https://anticompositetools.toolforge.org/hyphenator',
           'keywords': ['books', 'citation'],
           'author': [{'name': 'AntiCompositeNumber', 'wiki_username': None, 'developer_username': None, 'email': None, 'url': None}],
           'icon': None,
           'tool_type': None,
           'annotations': {'icon': None, 'tool_type': None}
         },
        {
           'name': 'toolforge-stashbot',
...(snip)...