glanceapp/glance · error

orderedMap: expected even number of content items, got %d

Error message

orderedMap: expected even number of content items, got %d

What it means

This error is returned by the custom orderedYAMLMap unmarshaler when a YAML mapping node contains an odd number of content items. In go-yaml, a MappingNode's Content slice always alternates key/value pairs, so an odd length means the YAML document itself is structurally malformed (e.g. a key with no value). It is essentially a defensive sanity check that fires before the key/value decode loop runs.

Source

Thrown at internal/glance/config.go:608

	maps.Copy(merged.data, self.data)

	for _, key := range other.keys {
		if _, exists := self.data[key]; !exists {
			merged.keys = append(merged.keys, key)
		}
	}
	maps.Copy(merged.data, other.data)

	return merged
}

func (om *orderedYAMLMap[K, V]) UnmarshalYAML(node *yaml.Node) error {
	if node.Kind != yaml.MappingNode {
		return fmt.Errorf("orderedMap: expected mapping node, got %d", node.Kind)
	}

	if len(node.Content)%2 != 0 {
		return fmt.Errorf("orderedMap: expected even number of content items, got %d", len(node.Content))
	}

	om.keys = make([]K, len(node.Content)/2)
	om.data = make(map[K]V, len(node.Content)/2)

	for i := 0; i < len(node.Content); i += 2 {
		keyNode := node.Content[i]
		valueNode := node.Content[i+1]

		var key K
		if err := keyNode.Decode(&key); err != nil {
			return fmt.Errorf("orderedMap: decoding key: %v", err)
		}

		if _, ok := om.data[key]; ok {
			return fmt.Errorf("orderedMap: duplicate key %v", key)
		}

View on GitHub (pinned to 91324e8de7)

Solutions

1. Check the config file near the mapping reported in the surrounding error for a key without a value and add the missing value or remove the key
2. Validate the YAML with a linter or `glance config-check`/re-parse with a strict YAML tool before running the app
3. If generating YAML programmatically, ensure every emitted key also emits a value node

Example fix

# before
theme:
  presets:
    my-theme:
# after
theme:
  presets:
    my-theme:
      color-scheme: dark

// Pre-validate config YAML structure before passing to glance
import "gopkg.in/yaml.v3"

func mappingIsBalanced(src []byte) error {
    var v any
    if err := yaml.Unmarshal(src, &v); err != nil {
        return err // syntax error surfaces here first
    }
    return nil
}

Catch the error at config load and surface file/line from the wrapped yaml error, then re-prompt the user/editor for a corrected file rather than retrying.

When it happens

Trigger: Unmarshalling any YAML mapping into an orderedYAMLMap field (theme presets, config maps) where the parsed node.Content has odd length. This only occurs with a corrupted YAML document or a malformed node produced by custom decoding logic, since go-yaml itself rejects odd mappings at parse time.

Common situations: Hand-edited glance.yml with a truncated mapping (e.g. a theme preset key with no properties), config files with unbalanced merge keys, or programmatic YAML generation that drops a value node.

Related errors

• URL is required
• nested groups are not supported
• split columns inside of groups are not supported
• source is required
• subreddit is required

AI-assisted analysis of glanceapp/glance@91324e8de7 (2026-08-15). Data as JSON: /api/errors/c2d81fae648090ed. Report an issue: GitHub.