エラー内容

22:33:12.005 [info]  Application elixir_ls_utils exited: :stopped

22:33:12.011 [info]  Application jason_vendored exited: :stopped

22:33:12.011 [info]  Application erl2ex exited: :stopped

22:33:12.011 [info]  Application forms exited: :stopped
[Warn  - 22:33:12] ** (RuntimeError) Unable to start ElixirLS due to an incomplete erlang installation. See https://github.com/elixir-lsp/elixir-ls/blob/master/guides/incomplete-installation.md#edoc-missing for guidance.
    (language_server 0.6.5) lib/language_server/cli.ex:31: ElixirLS.LanguageServer.CLI.start_language_server/0
    (language_server 0.6.5) lib/language_server/cli.ex:9: ElixirLS.LanguageServer.CLI.main/0
    (stdlib 3.14) erl_eval.erl:680: :erl_eval.do_apply/6
    (elixir 1.11.2) lib/code.ex:341: Code.eval_string_with_error_handling/3
[Error - 22:33:12] Connection to server got closed. Server will not be restarted.

解決方法

$ sudo apt-get install erlang erlang-dialyzer