vim-clap: Clap help_tags does not show search result

Environment (please complete the following information):

• OS: macOS
• (Neo)Vim version: Vim head Version
• vim-clap version: head Version
• Have you reproduced with a minimal vimrc: Yes
• Have you updated to the latest plugin version: Yes
• Have you upgraded to/compiled the latest Rust binary: ??? Yes

Describe the bug Clap help_tags can not perform search, just show

vim-clap: Vim(let):E906: not an open channel
vim-clap: Vim(let):E906: not an open channel
...

Clap debug

            has cargo: 1
            has maple: /Users/mark/.dot_vim/bundle/vim-clap/target/release/maple
           maple info: version 0.1.17 (git v0.17), built for x86_64-apple-darwin by rustc 1.43.1.

         has +python3: 1
has py dynamic module: 0
     Current FileType: 
Third Party Providers: []
       Global Options:
    let g:clap#autoload_dir = '/Users/mark/.dot_vim/bundle/vim-clap/autoload'
    let g:clap#provider_alias = {'gfiles': 'git_files', 'hist:': 'command_history', 'hist/': 'search_history'}
    let g:clap_cache_directory = '/Users/mark/.vim/cache/clap'
    let g:clap_disable_bottom_top = 0
    let g:clap_disable_matches_indicator = v:false
    let g:clap_disable_optional_async = v:false
    let g:clap_disable_run_rooter = v:false
    let g:clap_enable_icon = 0
    let g:clap_forerunner_status_sign = {'done': '•', 'running': '!', 'using_cache': '*'}
    let g:clap_insert_mode_only = 1
    let g:clap_layout = {'col': '10%', 'row': '20%', 'width': '80%', 'relative': 'editor', 'height': '30%'}
    let g:clap_multi_selection_warning_silent = 0
    let g:clap_no_matches_msg = 'NO MATCHES FOUND'
    let g:clap_open_action = {'ctrl-v': 'vsplit', 'ctrl-x': 'split', 'ctrl-t': 'tab split'}
    let g:clap_popup_border = 'rounded'
    let g:clap_preview_size = 5
    let g:clap_project_root_markers = ['.git', '.git/', '.hg', '.svn', '.bzr', '_darcs', '_FOSSIL_', '.fslckout', '.project', '.root']
    let g:clap_prompt_format = ' %provider_id%> '
    let g:clap_providers_relaunch_code = '@@'
    let g:clap_search_box_border_style = 'nil'
    let g:clap_search_box_border_symbols = {'nil': ['', ''], 'curve': ['', ''], 'arrow': ['', '']}
  Provider Variables:
    let g:clap_provider_grep_enable_icon = 0

To Reproduce

1. Type Clap help_tags
2. perform search, nothing happened
3. :messages show error vim-clap: Vim(let):E906: not an open channel