Unable to read .merlin file in sub-directory

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I'm trying to use `reason-vscode` for flow development but I ran into a bit of a snag. Here's a snippet of the debug.log that I think is applicable:
```
=== Project root: /Users/kevinbarabash/flow
Detected `opam` dependency manager for local use
Sending response {"id": 15, "jsonrpc": "2.0", "error": {"code": -32603, "message": "Unable to read /Users/kevinbarabash/flow/src/typing/.merlin"}}
Read message
{"jsonrpc":"2.0","id":16,"method":"textDocument/hover","params":{"textDocument":{"uri":"file:///Users/kevinbarabash/flow/src/typing/env.ml"},"position":{"line":1352,"character":40}}}
[server] Got a method textDocument/hover
[server] processing took 0.00596046447754ms
Found a `dune` file at /Users/kevinbarabash/flow/src/typing
]] Making a new jbuilder package at /Users/kevinbarabash/flow/src/typing
```

Start by reproducing the debug log for /Users/kevinbarabash/flow/src/typing/env.ml and inspect how the discovered dune file and sub-directory .merlin path are handled. Done means the language server reads the sub-directory configuration without the reported error and can process the hover request.

Written by the indexing model from the issue text.