No such file or directory error with ppx_expect

I'm using ppx_expect to test my Reason files. In any Reason module that includes let%expect_test I see the following build error:

type error here Line 1:
Error: I/O error: : No such file or directory

I'm building with esy. When I run the tests with esy dune runtest everything runs just fine. This problem only effects editing Reason files that use let%expect_test (ml files do not exhibit this issue). All other files work fine.

The entire build command from debug.log is too much to paste here, but the last part of the build command the output showing the error are:

{snip}
 -bin-annot -open NaismithSrc -open Core_kernel -open NaismithExt.Pipe -ppx '/src/reason-playground/naismith/_esy/default/store/b/naismith-6ce4e131/default/.ppx/c71d0a51e5287292e3bae7e7566a859b/ppx.exe --as-ppx --cookie '\''library-name="NaismithSrc"'\''' -impl /src/reason-playground/naismith/_esy/default/store/b/naismith-6ce4e131/.lsp/NaismithSrc__Repl.ast with pwd /src/reason-playground/naismith/src
Now loading /src/reason-playground/naismith/_esy/default/store/b/naismith-6ce4e131/.lsp/NaismithSrc__Repl.cmt
Size 55934
<< Making lastDefinitions with type error for file:///src/reason-playground/naismith/src/Repl.re
type error here Line 1:
Error: I/O error: : No such file or directory
Sending notification {"jsonrpc": "2.0", "method": "textDocument/publishDiagnostics", "params":{"uri": "file:///src/reason-playground/naismith/src/Repl.re", "diagnostics": [{"range": {"start": {"line": 0, "character": 0}, "end": {"line": 0, "character": 0}}, "message": "Line 1:\nError: I/O error: : No such file or directory", "severity": 1}]}}

If it helps, here's the output of esy ls-libs showing installed libraries and versions:

naismith@0.1.0 [build pending]
├── @esy-ocaml/reason@3.6.0 [built]
│   ├── reason.easy_format
│   ├── reason.cmdliner
│   └── reason
├── @opam/alcotest@opam:1.0.0 [built]
│   └── alcotest
├── @opam/base@opam:v0.13.0 [built]
│   ├── base.shadow_stdlib
│   ├── base.md5
│   ├── base.caml
│   ├── base.base_internalhash_types
│   └── base
├── @opam/core_kernel@opam:v0.13.0 [built]
│   ├── core_kernel.weak_pointer
│   ├── core_kernel.weak_hashtbl
│   ├── core_kernel.weak_array
│   ├── core_kernel.version_util
│   ├── core_kernel.uuid
│   ├── core_kernel.uopt
│   ├── core_kernel.unpack_buffer
│   ├── core_kernel.univ
│   ├── core_kernel.tuple_pool
│   ├── core_kernel.total_map
│   ├── core_kernel.timing_wheel
│   ├── core_kernel.thread_safe_queue
│   ├── core_kernel.thread_pool_cpu_affinity
│   ├── core_kernel.sexp_hidden_in_test
│   ├── core_kernel.rope
│   ├── core_kernel.pooled_hashtbl
│   ├── core_kernel.pairing_heap
│   ├── core_kernel.moption
│   ├── core_kernel.linked_stack
│   ├── core_kernel.limiter
│   ├── core_kernel.int_set
│   ├── core_kernel.hash_heap
│   ├── core_kernel.force_once
│   ├── core_kernel.flags
│   ├── core_kernel.fheap
│   ├── core_kernel.composition_infix
│   ├── core_kernel.bounded_int_table
│   ├── core_kernel.binary_packing
│   ├── core_kernel.base_for_tests
│   ├── core_kernel.balanced_reducer
│   └── core_kernel
├── @opam/dune@opam:2.2.0 [built]
│   ├── dune.configurator
│   └── dune
├── @opam/expect_test_helpers_kernel@opam:v0.13.0 [built]
│   ├── expect_test_helpers_kernel.expect_test_helpers_base
│   └── expect_test_helpers_kernel
├── @opam/fmt@opam:0.8.8 [built]
│   ├── fmt.tty
│   ├── fmt.top
│   ├── fmt.cli
│   └── fmt
├── @opam/menhir@opam:20200123 [built]
│   └── menhir
├── @opam/merlin@opam:3.3.3 [built]
│   └── merlin
├── @opam/odoc@opam:1.5.0 [built]
│   ├── odoc.xref
│   ├── odoc.parser
│   ├── odoc.odoc
│   ├── odoc.model
│   ├── odoc.loader
│   ├── odoc.html
│   ├── odoc.compat
│   └── odoc
├── @opam/patdiff@opam:v0.13.0 [built]
│   ├── patdiff.lib
│   └── patdiff
├── @opam/ppx_deriving@opam:4.4 [built]
│   ├── ppx_deriving.std
│   ├── ppx_deriving.show
│   ├── ppx_deriving.runtime
│   ├── ppx_deriving.ord
│   ├── ppx_deriving.map
│   ├── ppx_deriving.make
│   ├── ppx_deriving.iter
│   ├── ppx_deriving.fold
│   ├── ppx_deriving.eq
│   ├── ppx_deriving.enum
│   ├── ppx_deriving.create
│   ├── ppx_deriving.api
│   └── ppx_deriving
├── @opam/ppx_expect@opam:v0.13.0 [built]
│   ├── ppx_expect.payload
│   ├── ppx_expect.matcher
│   ├── ppx_expect.evaluator
│   ├── ppx_expect.config
│   ├── ppx_expect.common
│   ├── ppx_expect.collector
│   └── ppx_expect
├── @opam/rtop@opam:3.5.2 [built]
│   └── rtop
├── @opam/sedlex@opam:2.1 [built]
│   ├── sedlex.ppx
│   └── sedlex
├── @opam/stdio@opam:v0.13.0 [built]
│   └── stdio
├── @pesy/esy-pesy@0.1.0-alpha.5 [built]
│   ├── pesy--esy-pesy.utils
│   ├── pesy--esy-pesy.lib
│   ├── pesy--esy-pesy.errors
│   └── pesy--esy-pesy
├── @reason-native/console@0.1.0 [built]
│   ├── console.lib
│   └── console
├── @reason-native/pastel@0.3.0 [built]
│   ├── pastel.lib
│   ├── pastel.internal
│   └── pastel
├── @reason-native/rely@3.2.1 [built]
│   ├── rely.lib
│   ├── rely.internal
│   └── rely
├── ocaml@4.8.1000 [built]
└── refmterr@3.3.0 [built]
    ├── refmterr.lib
    └── refmterr

レポートに記載された esy セットアップで let%expect_test を含む Reason ファイルを編集してエラーを再現し、エディターの診断結果と esy dune runtest を比較します。レポートに示されている language server のビルドコマンドと、その ppx_expect の呼び出しを追跡します。Reason ファイルが I/O 診断を受けなくなり、既存のテストコマンドが引き続き成功すれば完了です。