JuliusBrussee/caveman · error

${label}:${lineNo}: nested line without an open block

Error message

${label}:${lineNo}: nested line without an open block

What it means

Thrown by the catalog parser when a line at indent 4 (the nested block level) appears while blockKey is null — i.e. no indent-2 key was left "open" as a valueless block header. Indent-4 content is only meaningful as the contents of a block key like " models:"; without one, the parser cannot tell which property the nested line belongs to.

Source

Thrown at scripts/generate-agent-catalog.mjs:87

    }
    if (row === null) throw new Error(`${label}:${lineNo}: indented line before any row`);
    if (indent === 2) {
      if (dash) throw new Error(`${label}:${lineNo}: unexpected sequence item at row level`);
      const entry = splitKeyValue(rest, label, lineNo);
      if (Object.prototype.hasOwnProperty.call(row, entry.key)) {
        throw new Error(`${label}:${lineNo}: duplicate key "${entry.key}"`);
      }
      if (entry.value === undefined) {
        blockKey = entry.key;
        row[entry.key] = undefined;
      } else {
        blockKey = null;
        row[entry.key] = entry.value;
      }
      continue;
    }
    if (indent === 4) {
      if (blockKey === null) throw new Error(`${label}:${lineNo}: nested line without an open block`);
      if (dash) {
        if (row[blockKey] === undefined) row[blockKey] = [];
        if (!Array.isArray(row[blockKey])) throw new Error(`${label}:${lineNo}: "${blockKey}" mixes map and sequence entries`);
        row[blockKey].push(rest);
        continue;
      }
      if (row[blockKey] === undefined) row[blockKey] = {};
      if (Array.isArray(row[blockKey]) || typeof row[blockKey] !== "object") {
        throw new Error(`${label}:${lineNo}: "${blockKey}" mixes map and sequence entries`);
      }
      const entry = splitKeyValue(rest, label, lineNo);
      if (entry.value === undefined) throw new Error(`${label}:${lineNo}: nesting deeper than two levels is not supported`);
      if (Object.prototype.hasOwnProperty.call(row[blockKey], entry.key)) {
        throw new Error(`${label}:${lineNo}: duplicate key "${blockKey}.${entry.key}"`);
      }
      row[blockKey][entry.key] = entry.value;
      continue;
    }

View on GitHub (pinned to 27d5a3981a)

Solutions

1. Insert the block header at indent 2 with no inline value above the nested lines: " models:" then the indent-4 items.
2. If the indent-4 line is really a row property, dedent it to 2 spaces.
3. Remove inline values from keys that are meant to open blocks — "key: value" closes the block, "key:" opens it.

Example fix

# before
- provider: anthropic
  models: all
    - claude-4

# after
- provider: anthropic
  models:
    - claude-4

function indent4AlwaysUnderOpenBlock(text) {
  let openBlock = false;
  for (const line of text.split("\n")) {
    if (/^ {2}[A-Za-z_][A-Za-z0-9_]*:\s*$/.test(line.replace(/\s+$/, ""))) openBlock = true;
    else if (/^ {2}\S/.test(line)) openBlock = false;
    else if (/^ {4}/.test(line) && !openBlock) return false;
  }
  return true;
}

try {
  parseCatalog(text);
} catch (err) {
  if (/nested line without an open block/.test(err.message)) {
    // add the valueless indent-2 key header above the indent-4 lines
  } else throw err;
}

When it happens

Trigger: Writing indent-4 lines directly after an inline-valued property, e.g. " models: default" followed by " - claude-4"; or deleting/commenting the " key:" header line while leaving its children.

Common situations: Editor auto-indent carrying 4 spaces onto a line that should be at 2; converting an inline value to a list but forgetting to strip the inline value; merge conflict cleanup removing the block header.

Related errors

• ${label}:${lineNo}: unexpected sequence item at row level
• ${label}:${lineNo}: unexpected indent of ${indent} spaces
• ${label}:${lineNo}: expected a top-level "- provider: ..." r
• ${label}:${lineNo}: row must start with an inline "provider"
• ${label}:${lineNo}: indented line before any row

AI-assisted analysis of JuliusBrussee/caveman@27d5a3981a (2026-08-15). Data as JSON: /api/errors/9186ae22c21dd595. Report an issue: GitHub.