biomejs/biome · error

found a token with no parent

Error message

found a token with no parent

What it means

Panic in the GraphQL format-on-type handler (graphql.rs:540). After finding the token at the offset, the handler calls token.parent(); tokens returned by token_at_offset on a parsed rowan tree always have a parent node because the tree root is a node. This panic is a defensive assertion for a detached/token-rooted tree that the normal parse path cannot produce.

Source

Thrown at crates/biome_service/src/file_handlers/graphql.rs:540

        // File is empty, do nothing
        TokenAtOffset::None => panic!("empty file"),
        TokenAtOffset::Single(token) => token,
        // The cursor should be right after the closing character that was just typed,
        // select the previous token as the correct one
        TokenAtOffset::Between(token, _) => token,
    };

    if token.text_trimmed_range().end() != offset {
        return Ok(format_on_type_noop(offset));
    }

    if !matches_on_type_char(token.text_trimmed()) {
        return Ok(format_on_type_noop(offset));
    }

    let root_node = match token.parent() {
        Some(node) => node,
        None => panic!("found a token with no parent"),
    };

    if root_node
        .ancestors()
        .any(|node: GraphqlSyntaxNode| node.kind().is_bogus())
    {
        return Ok(format_on_type_noop(offset));
    }

    let formatting_root = root_node
        .ancestors()
        .find(|node: &GraphqlSyntaxNode| {
            node.parent()
                .is_some_and(|parent| parent.kind() == GraphqlSyntaxKind::GRAPHQL_ROOT)
        })
        .unwrap_or(root_node);

    let printed = biome_graphql_formatter::format_range(

View on GitHub (pinned to 405dedb0ff)

Solutions

1. Update to the latest Biome release
2. File an issue with the exact document and keystroke if you can reproduce it (https://github.com/biomejs/biome/issues)
3. If embedding biome_service, wrap on-type format calls in catch_unwind and degrade to no formatting

// LSP client - ignore a failed on-type format request
try {
  await client.sendRequest('textDocument/onTypeFormatted', params);
} catch {
  // no-op: keep typing responsive, do not surface the error
}

When it happens

Trigger: Not reachable through normal editor traffic; would require a detached token or a token-rooted syntax tree, neither of which tree.token_at_offset produces.

Common situations: Practically never observed; only plausible with hand-built trees in tests or after parser internals changed.

Related errors

• found a token with no parent
• empty file
• found a token with no parent
• found a token with no parent
• found a token with no parent

AI-assisted analysis of biomejs/biome@405dedb0ff (2026-08-20). Data as JSON: /api/errors/6d6e89de4a38628e. Report an issue: GitHub.