grafana/k6 · error

[options] must be an object

Error message

[options] must be an object

What it means

Error "[options] must be an object" thrown in grafana/k6.

Source

Thrown at internal/js/modules/k6/websockets/blob.go:43

func (r *WebSocketsAPI) blob(call sobek.ConstructorCall) *sobek.Object {
	rt := r.vu.Runtime()

	b := &blob{data: new(bytes.Buffer)}
	var blobParts []any
	if len(call.Arguments) > 0 {
		if err := rt.ExportTo(call.Arguments[0], &blobParts); err != nil {
			common.Throw(rt, fmt.Errorf("failed to process [blobParts]: %w", err))
		}
	}

	if len(blobParts) > 0 {
		r.fillData(b, blobParts, call)
	}

	if len(call.Arguments) > 1 && !sobek.IsUndefined(call.Arguments[1]) {
		opts := call.Arguments[1]
		if !isObject(opts) {
			common.Throw(rt, errors.New("[options] must be an object"))
		}

		typeOpt := opts.ToObject(rt).Get("type")
		if !sobek.IsUndefined(typeOpt) {
			b.typ = typeOpt.String()
		}
	}

	obj := rt.NewObject()
	must(rt, obj.DefineAccessorProperty("size", rt.ToValue(func() sobek.Value {
		return rt.ToValue(b.data.Len())
	}), nil, sobek.FLAG_FALSE, sobek.FLAG_TRUE))
	must(rt, obj.DefineAccessorProperty("type", rt.ToValue(func() sobek.Value {
		return rt.ToValue(b.typ)
	}), nil, sobek.FLAG_FALSE, sobek.FLAG_TRUE))

	must(rt, obj.Set("arrayBuffer", func(_ sobek.FunctionCall) sobek.Value {
		promise, resolve, _ := rt.NewPromise()

View on GitHub (pinned to 93accf6570)

When it happens

Trigger: Thrown at internal/js/modules/k6/websockets/blob.go:43 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/7be4fe29b2e907a5. Report an issue: GitHub.