tomnomnom/gron · error

cannot merge array with non-array

Error message

cannot merge array with non-array

What it means

recursiveMerge was asked to merge a []interface{} with a value whose dynamic type is not a slice, which cannot be combined. The input assigns both an array and a non-array (object or scalar) to the same indexed key path.

Source

Thrown at ungron.go:456

		return nil, fmt.Errorf("unexpected token `%s`", t.text)
	}
}

// recursiveMerge merges maps and slices, or returns b for scalars
func recursiveMerge(a, b interface{}) (interface{}, error) {
	switch a.(type) {

	case map[string]interface{}:
		bMap, ok := b.(map[string]interface{})
		if !ok {
			return nil, fmt.Errorf("cannot merge object with non-object")
		}
		return recursiveMapMerge(a.(map[string]interface{}), bMap)

	case []interface{}:
		bSlice, ok := b.([]interface{})
		if !ok {
			return nil, fmt.Errorf("cannot merge array with non-array")
		}
		return recursiveSliceMerge(a.([]interface{}), bSlice)

	case string, int, float64, bool, nil, json.Number:
		// Can't merge them, second one wins
		return b, nil

	default:
		return nil, fmt.Errorf("unexpected data type for merge: `%s`", reflect.TypeOf(a))
	}
}

// recursiveMapMerge recursively merges map[string]interface{} values
func recursiveMapMerge(a, b map[string]interface{}) (map[string]interface{}, error) {
	// Merge keys from b into a
	for k, v := range b {
		_, exists := a[k]
		if !exists {

View on GitHub (pinned to 88a6234ea2)

Solutions

1. Ensure the conflicting key path is an array in every statement that mentions it
2. Change one of the conflicting assignments so the types agree

When it happens

Trigger: Thrown at ungron.go:456 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of tomnomnom/gron@88a6234ea2 (2026-09-06). Data as JSON: /api/errors/5dbf5fb550744c28. Report an issue: GitHub.