Error "connection got disposed off" (but not on save as in #247 and #142 but on start/load)

I am having the same (or very similar errors) as mentioned in #142 and #247, but not just on save but when I load an OCaml file. That is for me the VSCode plugin doesn’t work at all. Some notes on my environment:

• I am on Windows 10 and using a MinGW cross opam running on cygwin from https://fdopen.github.io/opam-repository-mingw/installation/
• I did opam install merlin and opam install ocp-indent
• I did not install any OCaml language server (i.e. I did not do npm install -g ocaml-language-server nor do I have nodejs installed) since I didn’t find anything in the installation instructions which recommends this (I just found the reference in some comments on #247 and #142).
• I call VSCode (code.cmd) from within cygwin from the root folder of a simple OCaml project and with ocamlmerlin in the path. The project I used for testing is yojson-master.
• VSCode seems to start ocamlmerlin, but then I get the below errors
• If I call VScode without having ocamlmerlin in the path, I get an error that it can’t find ocamlmerlin instead
• I am doing OCaml development, not Reason

The error message I get (within 1s after loading any OCaml file):

events.js:167
      throw er; // Unhandled 'error' event
      ^

Error [ERR_STREAM_DESTROYED]: Cannot call write after a stream was destroyed
    at doWrite (_stream_writable.js:406:19)
    at writeOrBuffer (_stream_writable.js:394:5)
    at Socket.Writable.write (_stream_writable.js:294:11)
    at Interface._writeToOutput (readline.js:300:17)
    at Interface.prompt (readline.js:264:10)
    at Interface.question (readline.js:277:12)
    at worker (c:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\ocaml-language-server\bin\server\processes\merlin.js:52:31)
    at c:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\async\dist\async.js:4082:9
    at process (c:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\async\dist\async.js:2330:17)
    at Immediate.<anonymous> (c:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\async\dist\async.js:119:16)
Emitted 'error' event at:
    at onwriteError (_stream_writable.js:425:12)
    at onwrite (_stream_writable.js:456:5)
    at doWrite (_stream_writable.js:406:11)
    at writeOrBuffer (_stream_writable.js:394:5)
    [... lines matching original stack trace ...]
    at c:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\async\dist\async.js:4082:9
[Error - 10:24:01] Connection to server got closed. Server will not be restarted.
[Error - 10:24:01] Request textDocument/codeAction failed.
Error: Connection got disposed.
	at Object.dispose (C:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\vscode-jsonrpc\lib\main.js:825:25)
	at Object.dispose (C:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\vscode-languageclient\lib\client.js:57:35)
	at LanguageClient.handleConnectionClosed (C:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\vscode-languageclient\lib\client.js:1954:42)
	at LanguageClient.handleConnectionClosed (C:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\vscode-languageclient\lib\main.js:126:15)
	at closeHandler (C:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\vscode-languageclient\lib\client.js:1941:18)
	at CallbackList.invoke (C:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\vscode-jsonrpc\lib\events.js:71:39)
	at Emitter.fire (C:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\vscode-jsonrpc\lib\events.js:135:36)
	at closeHandler (C:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\vscode-jsonrpc\lib\main.js:221:26)
	at CallbackList.invoke (C:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\vscode-jsonrpc\lib\events.js:71:39)
	at Emitter.fire (C:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\vscode-jsonrpc\lib\events.js:135:36)
	at IPCMessageReader.AbstractMessageReader.fireClose (C:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\vscode-jsonrpc\lib\messageReader.js:135:27)
	at ChildProcess.<anonymous> (C:\Users\soegtrop\.vscode\extensions\freebroccolo.reasonml-1.0.38\node_modules\vscode-jsonrpc\lib\messageReader.js:253:61)
	at ChildProcess.emit (events.js:187:15)
	at maybeClose (internal/child_process.js:961:16)
	at Process.ChildProcess._handle.onexit (internal/child_process.js:248:5)

[mnxn]

@MSoegtropIMC @cqfllp This sounds related to #236

Try setting reason.path.ocamlmerlin to “ocamlmerlin-server”

[MSoegtropIMC]

P.S.: There is one more caveat: I found that sometimes VSCode leaves hidden processes after closing and if it is started from the command line, it might pick up this hidden process rather than creating a new one. This has the effect that VSCode has the wrong environment, notably possibly a wrong path without ocamlmerlin-server. In case you have unreproducible errors, open a terminal from VSCode and inspect that PATH. If the PATH is wrong, close VSCode, check that there are no VSCode processes left (or kill them) and restart.