Autocomplete not working

* I installed extension;
* I insalled luacheck;
* I added `"lua.luacheckPath": "/usr/bin/luacheck"` in my `settings.json` ;
* I setup environment variables LUA_PATH and LUA_CPATH;
* I created file `test.lua`:

```lua
local q = 'Qwerty'
-- Then i typed «q:lo» and and auto-completion didn't work
```