UnhandledRejection: Cannot read property 'length' of null

[ronakg]

I'm using coc.nvim with a custom language server and I keep getting this error from time to time.

How do I go about investigating this issue?

[coc.nvim]: UnhandledRejection: Cannot read property 'length' of null
TypeError: Cannot read property 'length' of null
    at ax.getTokenRanges (/vim/plugged/coc.nvim/build/index.js:297:19887)
    at ax.requestRangeHighlights (/vim/plugged/coc.nvim/build/index.js:297:24212)
    at async ax.doRangeHighlight (/vim/plugged/coc.nvim/build/index.js:297:22419)
    at async ax.doHighlight (/vim/plugged/coc.nvim/build/index.js:297:21320)

[NoahTheDuke]

https://github.com/neoclide/coc.nvim/wiki/Debug-language-server
and
https://github.com/neoclide/coc.nvim/wiki/Debug-coc.nvim

[ronakg]

Thanks. I enabled verbose log output and capture these logs from a Jump to Reference command.

Looks like this is related to semantic tokens.

2022-05-31T13:44:24.156 INFO (pid:905829) [attach] - receive notification: jumpReferences []
2022-05-31T13:44:25.240 WARN (pid:905829) [plugin] - Slow action "jumpReferences" cost 1082ms
2022-05-31T13:44:25.241 INFO (pid:905829) [attach] - receive notification: openList [ '--normal', '--auto-preview', 'location' ]
2022-05-31T13:44:25.331 DEBUG (pid:905829) [core-documents] - buffer created 10 false list:/location
2022-05-31T13:44:27.504 DEBUG (pid:905829) [core-documents] - document detach 10 list:/location
2022-05-31T13:44:27.761 DEBUG (pid:905829) [core-documents] - buffer created 14 true file:<redacted>
2022-05-31T13:44:27.761 DEBUG (pid:905829) [core-editors] - editor created winid & bufnr & tabnr:  1000 14 1
2022-05-31T13:44:28.009 ERROR (pid:905829) [server] - unhandledRejection  Promise {
  <rejected> TypeError: Cannot read property 'length' of null
      at ax.getTokenRanges (/vim/plugged/coc.nvim/build/index.js:297:19887)
      at ax.requestRangeHighlights (/vim/plugged/coc.nvim/build/index.js:297:24212)
      at async ax.doRangeHighlight (/vim/plugged/coc.nvim/build/index.js:297:22419)
      at async ax.doHighlight (/vim/plugged/coc.nvim/build/index.js:297:21320)
} TypeError: Cannot read property 'length' of null
    at ax.getTokenRanges (/vim/plugged/coc.nvim/build/index.js:297:19887)
    at ax.requestRangeHighlights (/vim/plugged/coc.nvim/build/index.js:297:24212)
    at async ax.doRangeHighlight (/vim/plugged/coc.nvim/build/index.js:297:22419)
    at async ax.doHighlight (/vim/plugged/coc.nvim/build/index.js:297:21320)
2022-05-31T13:44:29.616 INFO (pid:905829) [attach] - receive notification: highlight []
2022-05-31T13:44:30.506 ERROR (pid:905829) [events] - Error on event: CursorMoved TypeError: Cannot read property 'length' of null
    at ax.getTokenRanges (/vim/plugged/coc.nvim/build/index.js:297:19887)
    at ax.requestRangeHighlights (/vim/plugged/coc.nvim/build/index.js:297:24212)
    at async ax.doRangeHighlight (/vim/plugged/coc.nvim/build/index.js:297:22419)
    at async ax.onCursorMoved (/vim/plugged/coc.nvim/build/index.js:297:23761)
    at async /vim/plugged/coc.nvim/build/index.js:297:27013
2022-05-31T13:44:30.898 ERROR (pid:905829) [events] - Error on event: CursorMoved TypeError: Cannot read property 'length' of null
    at ax.getTokenRanges (/vim/plugged/coc.nvim/build/index.js:297:19887)
    at ax.requestRangeHighlights (/vim/plugged/coc.nvim/build/index.js:297:24212)
    at async ax.doRangeHighlight (/vim/plugged/coc.nvim/build/index.js:297:22419)
    at async ax.onCursorMoved (/vim/plugged/coc.nvim/build/index.js:297:23761)
    at async /vim/plugged/coc.nvim/build/index.js:297:27013
2022-05-31T13:44:31.097 INFO (pid:905829) [attach] - receive notification: highlight []
2022-05-31T13:44:31.408 ERROR (pid:905829) [events] - Error on event: CursorMoved TypeError: Cannot read property 'length' of null
    at ax.getTokenRanges (/vim/plugged/coc.nvim/build/index.js:297:19887)
    at ax.requestRangeHighlights (/vim/plugged/coc.nvim/build/index.js:297:24212)
    at async ax.doRangeHighlight (/vim/plugged/coc.nvim/build/index.js:297:22419)
    at async ax.onCursorMoved (/vim/plugged/coc.nvim/build/index.js:297:23761)
    at async /vim/plugged/coc.nvim/build/index.js:297:27013
2022-05-31T13:44:31.796 ERROR (pid:905829) [events] - Error on event: CursorMoved TypeError: Cannot read property 'length' of null
    at ax.getTokenRanges (/vim/plugged/coc.nvim/build/index.js:297:19887)
    at ax.requestRangeHighlights (/vim/plugged/coc.nvim/build/index.js:297:24212)
    at async ax.doRangeHighlight (/vim/plugged/coc.nvim/build/index.js:297:22419)
    at async ax.onCursorMoved (/vim/plugged/coc.nvim/build/index.js:297:23761)
    at async /vim/plugged/coc.nvim/build/index.js:297:27013

[NoahTheDuke]

I would suggest adding this to your .vimrc before you load coc.nvim:

let g:node_client_debug = 1
let $NVIM_COC_LOG_LEVEL='debug'
let $NVIM_COC_LOG_FILE = '/tmp/coc-nvim.log'
let g:coc_node_args = ['-r', expand('~/.config/yarn/global/node_modules/source-map-support/register')]

and then in a second terminal window, calling tail -f /tmp/coc-nvim.log and seeing what it says as you perform actions. It'll automatically follow when you run :CocRestart and edit your code. It's the way I built coc-clojure at least.

[ronakg]

4a7b75a fixed this issue.