Issue title: attempt to call field "cmp_format" ( a nil value)
 Issue body: When I want open the nvim, I get this error.

`
 Error detected while processing /home/auto/.config/nvim/init.lua:                                                                                                 E5113: Error while calling lua chunk: /home/auto/.config/nvim/lua/lsp/ui.lua:117: attempt to call field 'cmp_format' (a nil value)                                                    stack traceback:                                                                                                                                                                              /home/auto/.config/nvim/lua/lsp/ui.lua:117: in main chunk                                                                                                                     
        [C]: in function 'require'                                                                                                                                                    
        /home/auto/.config/nvim/lua/lsp/cmp.lua:43: in main chunk                                                                                                                     
        [C]: in function 'require'                                                                                                                                                    
        /home/auto/.config/nvim/init.lua:27: in main chunk                                                                                                                            
Press ENTER or type command to continue 
`
Can you give me some advise?
 Comments: 
 Comment 0: `attempt to call field 'cmp_format' (a nil value) `

cmp_format is a method of lspkind

you should try uninstall lspkind first, then reinstall it

`use("onsails/lspkind-nvim")`


 Comment 1: 已经解决了，我清除了所有插件，然后重新安装，之后没有问题了。多谢帮忙。
{'source': 'GithubIssues', 'repo_name_with_owner': 'nshen/learn-neovim-lua', 'issue_id': 1252459142, 'repo_stars': 677.0}