oraios/serena · error · ValueError

ls_specific_settings.typescript_vts.initialization_options m

Error message

ls_specific_settings.typescript_vts.initialization_options must be a dict, got {type(opts).__name__}

What it means

Thrown as ValueError when user-supplied configuration ls_specific_settings.typescript_vts.initialization_options is not None but is also not a dict. The VTS language server can only merge dict-shaped initialization options into its initialize params.

Source

Thrown at src/solidlsp/language_servers/vts_language_server.py:137

        vts_executable_path = os.path.join(vts_ls_dir, "node_modules", ".bin", "vtsls")

        assert os.path.exists(vts_executable_path), "vtsls executable not found. Please install @vtsls/language-server and try again."
        return f"{vts_executable_path} --stdio"

    @property
    def _initialization_options(self) -> dict:
        """
        Validated user-provided ``initializationOptions``.

        :raises ValueError: if ``ls_specific_settings.typescript_vts.initialization_options``
            is set to a value that is not a dict.
        """
        opts = self._custom_settings.get("initialization_options")
        if opts is None:
            return {}
        if not isinstance(opts, dict):
            raise ValueError(f"ls_specific_settings.typescript_vts.initialization_options must be a dict, got {type(opts).__name__}")
        return opts

    def _create_base_initialize_params(self) -> dict:
        """
        Returns the initialize params for the VTS Language Server.

        If ``initialization_options`` is set in ``ls_specific_settings["typescript_vts"]``,
        it is forwarded verbatim as LSP ``initializationOptions``.
        """
        initialize_params: dict = {
            "locale": "en",
            "initializationOptions": {
                "preferences": {
                    "disableAutomaticTypingAcquisition": True,
                },
            },
            "capabilities": {
                "textDocument": {

View on GitHub (pinned to 7fcbca7e62)

Solutions

Change initialization_options in ls_specific_settings.typescript_vts to a proper mapping/dict.
Unquote stringified JSON objects (e.g. "{'preferStubs': true}" → {'preferStubs': true}).
If no options are needed, remove the key entirely rather than setting it to a non-dict; None/absent returns {}.
Validate the config schema before constructing the language server.

Example fix

// before
settings = {"ls_specific_settings": {"typescript_vts": {"initialization_options": "preferStubs=true"}}}
// after
settings = {"ls_specific_settings": {"typescript_vts": {"initialization_options": {"preferStubs": True}}}}

Defensive patterns

Strategy: validation

Validate before calling

opts = settings.get("ls_specific_settings", {}).get("typescript_vts", {}).get("initialization_options")
if opts is not None and not isinstance(opts, dict):
    raise TypeError("typescript_vts.initialization_options must be a dict")

Type guard

def is_init_options(value: object) -> bool:
    return value is None or isinstance(value, dict)

Try / catch

try:
    ls = SolidLSP("vts", repo_path, settings)
except ValueError as e:
    if "initialization_options must be a dict" in str(e):
        settings["ls_specific_settings"]["typescript_vts"]["initialization_options"] = {}
        ls = SolidLSP("vts", repo_path, settings)
    else:
        raise

Prevention

Validate config against a schema (pydantic/jsonschema) at load time.
Beware YAML/TOML indentation making nested objects into strings.
Omit initialization_options entirely when not needed instead of passing a scalar.
Add a unit test that loads your production config through the server constructor.

When it happens

Trigger: Passing config where initialization_options under typescript_vts is a string, list, number, or bool; _initialization_options reads self._custom_settings["initialization_options"] and raises on the type mismatch.

Common situations: YAML/JSON config where options were written as a quoted string; hand-editing config and dropping the braces around a nested object; copying TOML/YAML settings with wrong indentation so the value becomes a scalar.

Related errors

AI-assisted analysis of oraios/serena@7fcbca7e62 (2026-08-29). Data as JSON: /api/errors/9d7b6d772cb84519. Report an issue: GitHub.