:MerlinTypeOf raises error with some ReasonReact components

[johnridesabike]

I just set this up with VimBox, and it seems to be working well except for :MerlinTypeOf.

Steps to reproduce

I'm not sure exactly how to reproduce, since occasionally :MerlinTypeOf works, but these steps seem to work.

1. Install the project (I'm using bs-platform 7.3)

bsb -init bs-sample -theme react-starter
cd bs-sample
npm i

Create an esy.json

{
  "devDependencies": {
    "ocaml": "4.6.x",
    "@opam/reason": "*",
    "@opam/merlin": "*"
  }
}

esy install
esy mvim .
npm run start

2. It seems to only consistently happen when a component is inside a nested module (I could be wrong). Add this to src/App.re:

module A = {
  [@react.component]
  let make = () => <div />;
};

Hover over make and type :MerlinTypeOf.

The output

Error detected while processing function merlin#TypeOf:
line    4:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/Users/x/.esy/3______________________________________________________________/i/opam__s__merlin-opam__c__3.3.4-9cf3482f/share/merlin/vim/autoload/merlin.py", line
627, in vim_type_enclosing
    track_verbosity=True
  File "/Users/x/.esy/3______________________________________________________________/i/opam__s__merlin-opam__c__3.3.4-9cf3482f/share/merlin/vim/autoload/merlin.py", line
173, in command2
    result = json.loads(merlin_exec(cmdline,input=content))
  File "/Users/x/.esy/3______________________________________________________________/i/opam__s__merlin-opam__c__3.3.4-9cf3482f/share/merlin/vim/autoload/merlin.py", line
137, in merlin_exec
    (response, errors) = process.communicate(input=input)
  File "/usr/local/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 964, in communicate
    stdout, stderr = self._communicate(input, endtime, timeout)
  File "/usr/local/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 1755, in _communicate
    self.stdout.errors)
  File "/usr/local/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 841, in _translate_newlines
    data = data.decode(encoding, errors)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x84 in position 161: invalid start byte
line    5:
E121: Undefined variable: l:type
E116: Invalid arguments for function <SNR>167_ShowTypeEnclosing

Other information

All of the other Merlin features seem to work fine, go-to-location, autocomplete, etc.

Running :MerlinTypeOf works fine for other values in the same file, just not A.make.

In some modules in another project, running :MerlinTypeOf in any value inside a component function doesn't work. However I can't figure out the exact steps to reproduce that.

I'm still figuring out my Vim+Reason configuration, so I hope this isn't a user error. I'm happy to provide more information if necessary.

[johnridesabike]

After some digging, I think this may be outside the scope of vim-reasonml, and may be a larger issue with Merlin and BuckleScript ocaml/merlin#617