"Pattern not found" when trying autocomplete and go-langserver

[muni-corn]

• Did you upgrade to latest plugin version? Yes

• Did you upgrade to/compile latest binary? Run shell command bin/languageclient --version to get its version number. 0.1.131

• (Neovim users only) Did you check output of :checkhealth LanguageClient? Yes, everything is OK

• Did you check troubleshooting? Yes, problem persists

Describe the bug

Omnicompletion with gocode and go-langserver returns Pattern not found when using keyboard shortcut

Environment

• neovim version (nvim --version): NVIM v0.3.1

• This plugin version (git rev-parse --short HEAD): f228111

• This plugin's binary version (bin/languageclient --version): 0.1.131

• Minimal vimrc content (A minimal vimrc is the smallest vimrc that could reproduce the issue. Refer to an example [here][min-vimrc.vim]):

  
  call plug#begin('~/.local/share/nvim/plugged')
  
  Plug 'Shougo/deoplete.nvim', { 'do': ':UpdateRemotePlugins' }
  Plug 'autozimu/LanguageClient-neovim', {
    \ 'branch': 'next',
    \ 'do': 'bash install.sh',
    \ }
  
  call plug#end()
  
  " Always draw sign column. Prevent buffer moving when adding/deleting sign.
  set signcolumn=yes
  
  let g:LanguageClient_serverCommands = {
    \ 'go': ['/home/harrisonthorne/go/bin/go-langserver', '-gocodecompletion'],
    \ }
  let g:LanguageClient_loggingLevel = 'INFO'
  let g:LanguageClient_loggingFile =  expand('~/.local/share/nvim/LanguageClient.log')
  let g:LanguageClient_serverStderr = expand('~/.local/share/nvim/LanguageServer.log')

- Language server link and version:
go-langserver, version v3-dev
https://github.com/sourcegraph/go-langserver

[min-vimrc.vim]: https://github.com/autozimu/LanguageClient-neovim/blob/next/min-vimrc.vim

## To Reproduce
Steps to reproduce the behavior:
1. Create/Fetch example project
2. Start nvim, `nvim -u min-vimrc.vim`
3. Make sure deoplete is installed, go-langserver is running with `:LanguageClientStart`
4. Problem is intermittent. Try omnicompletion throughout a project, and on occasion, Neovim will print `Pattern not found` immediately after offering completion options (Pmenu will disappear)

## Current behavior
Neovim intermittently prints `Pattern not found` when executing omnicompletion. Interestingly, the completion options will appear briefly and then disappear, where Neovim outputs `Pattern not found`. Or, other times, completion options will not show at all.

## Expected behavior
Expect LanguageClient to supply completion options to omnicompletion without fail

[muni-corn]

UPDATE: Seems that starting gocode manually mitigates the issue. How can I start go-langserver and gocode at the same time under g:LanguageClient_serverCommands?