BoundaryML/baml · error · LspError

-32602

-32602

Error message

Invalid params: {0}

What it means

LspError::InvalidParams is returned when a request's parameters are malformed: a bad position, an out-of-range range, or any param that fails structural validation. It maps to the LSP InvalidParams code -32602 and prefixes the payload with 'Invalid params:'. It is distinct from InvalidCommandArguments, which covers executeCommand payloads specifically.

Source

Thrown at baml_language/crates/baml_lsp/src/error.rs:57

    NoRootForPath(PathBuf),
    /// Cancellation claimed the response while the request was queued or
    /// running (LSP `RequestCanceled`, `-32800`).
    #[error("Request canceled: {0}")]
    RequestCanceled(String),
    /// The request's snapshot became stale under an applied source change
    /// (LSP `ContentModified`, `-32801`).
    #[error("Content modified: {0}")]
    ContentModified(String),
    /// A valid request that cannot be served right now (LSP `RequestFailed`,
    /// `-32803`).
    #[error("{0}")]
    RequestFailed(String),
    /// Violated invariants, panics, serialization (LSP `InternalError`,
    /// `-32603`).
    #[error("Internal error: {0}")]
    Internal(String),
    /// Malformed params, position, or range (LSP `InvalidParams`, `-32602`).
    #[error("Invalid params: {0}")]
    InvalidParams(String),
    /// A request before `initialize` completed (LSP `ServerNotInitialized`,
    /// `-32002`).
    #[error("Server not initialized: {0}")]
    ServerNotInitialized(String),
}

impl LspError {
    /// The one LSP error-code mapping.
    #[must_use]
    pub fn to_response_error(&self) -> lsp_server::ResponseError {
        use lsp_server::ErrorCode;
        let code = match self {
            LspError::NotificationExtractError(_)
            | LspError::RequestExtractError(_)
            | LspError::InvalidCommandArguments { .. }
            | LspError::InvalidParams(_) => ErrorCode::InvalidParams,
            LspError::NotificationNotSupported(_) | LspError::RequestNotSupported(_) => {

View on GitHub (pinned to bd85ce9dee)

Solutions

1. Clamp/validate positions against the current document version's line count and line lengths before sending.
2. Ensure LSP positions are 0-based (line 0, character 0 is the first character of the file).
3. Re-read the latest document version from the client before computing positions or ranges.
4. Validate request params against the LSP schema for the method being called.

Example fix

// before
const params = { position: { line: 1, character: 0 } }; // 1-based guess
// after
const params = { position: { line: 0, character: 0 } }; // LSP positions are 0-based

function inBounds(position, docLines) {
  return position.line >= 0 && position.line < docLines.length &&
    position.character >= 0 && position.character <= docLines[position.line].length;
}

function isValidPosition(p) {
  return p != null && Number.isInteger(p.line) && p.line >= 0 &&
    Number.isInteger(p.character) && p.character >= 0;
}

try {
  return await request('textDocument/hover', { textDocument, position });
} catch (e) {
  if (e.code === -32602 || /Invalid params:/.test(e.message ?? '')) {
    console.warn('Bad params for hover:', { textDocument, position });
    return null;
  }
  throw e;
}

When it happens

Trigger: A textDocument position request sent with line/character beyond the document's bounds; missing required fields in request params; params that fail JSON deserialization into the request's expected type.

Common situations: Clients using stale document contents to compute positions after an edit; 0-based vs 1-based line/character confusion in custom tooling; null or undefined fields passed where structured values are required.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• {0}
• Invalid command arguments for command: {command}: {message}
• Path is invalid: {}: {message}
• -32800
• -32002

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/56f117678a261d37. Report an issue: GitHub.