Goto defintion/find reference doesn't work

Hi,

I am on nvim 0.5.0 and I try to use the plugin.
I get error on every gotodefintion and goto reference I try.
This is in the log:

```
## Output channel: vimlsp

events.js:298
throw er; // Unhandled 'error' event
^

Error [ERR_IPC_CHANNEL_CLOSED]: Channel closed
at process.target.send (internal/child_process.js:686:16)
at t._next (/Users/eyalkarni/.config/coc/extensions/node_modules/coc-vimlsp/out/scan.js:50:146211)
at t.__tryOrUnsub (/Users/eyalkarni/.config/coc/extensions/node_modules/coc-vimlsp/out/scan.js:35:62808)
at t.next (/Users/eyalkarni/.config/coc/extensions/node_modules/coc-vimlsp/out/scan.js:35:61915)
at t._next (/Users/eyalkarni/.config/coc/extensions/node_modules/coc-vimlsp/out/scan.js:35:60945)
at t.next (/Users/eyalkarni/.config/coc/extensions/node_modules/coc-vimlsp/out/scan.js:35:60616)
at t._next (/Users/eyalkarni/.config/coc/extensions/node_modules/coc-vimlsp/out/scan.js:50:55668)
at t.next (/Users/eyalkarni/.config/coc/extensions/node_modules/coc-vimlsp/out/scan.js:35:60616)
at t.notifyNext (/Users/eyalkarni/.config/coc/extensions/node_modules/coc-vimlsp/out/scan.js:50:45139)
at t._next (/Users/eyalkarni/.config/coc/extensions/node_modules/coc-vimlsp/out/scan.js:50:40619)
Emitted 'error' event on process instance at:
at internal/child_process.js:690:35
at processTicksAndRejections (internal/process/task_queues.js:79:11) {
code: 'ERR_IPC_CHANNEL_CLOSED'
}
```

Reproduce the failure on Neovim 0.5.0 using go-to-definition and go-to-reference, then inspect the vimlsp log and coc-vimlsp/out/scan.js around the reported IPC error. Done means both navigation commands work without ERR_IPC_CHANNEL_CLOSED.

Written by the indexing model from the issue text.