Make browser launch options optional

So that users can launch a browser without giving any options:

  const browser = chromium.launch();

Author: inancgumus

chromium/browser_type.go

@@ -131,9 +131,8 @@ func (b *BrowserType) Launch(opts goja.Value) api.Browser {
 	if b.logger, err = makeLogger(ctx); err != nil {
 		k6ext.Panic(ctx, "setting up logger: %w", err)
 	}
-
 	launchOpts := common.NewLaunchOptions(k6ext.OnCloud())
-	if err := launchOpts.Parse(ctx, opts, b.logger); err != nil {
+	if err := launchOpts.Parse(ctx, b.logger, opts); err != nil {
 		k6ext.Panic(ctx, "parsing launch options: %w", err)
 	}
 	ctx = common.WithLaunchOptions(ctx, launchOpts)

common/browser_options.go

@@ -2,7 +2,6 @@ package common
 
 import (
 	"context"
-	"errors"
 	"time"
 
 	"github.com/dop251/goja"
@@ -55,9 +54,10 @@ func NewLaunchOptions(onCloud bool) *LaunchOptions {
 }
 
 // Parse parses launch options from a JS object.
-func (l *LaunchOptions) Parse(ctx context.Context, opts goja.Value, logger *log.Logger) error { //nolint:cyclop
+func (l *LaunchOptions) Parse(ctx context.Context, logger *log.Logger, opts goja.Value) error { //nolint:cyclop
+	// when opts is nil, we just return the default options without error.
 	if !gojaValueExists(opts) {
-		return errors.New("LaunchOptions does not exist in the runtime")
+		return nil
 	}
 	var (
 		rt       = k6ext.Runtime(ctx)

common/browser_options_test.go

@@ -253,7 +253,7 @@ func TestBrowserLaunchOptionsParse(t *testing.T) {
 				vu = k6test.NewVU(t)
 				lo = NewLaunchOptions(tt.onCloud)
 			)
-			err := lo.Parse(vu.Context(), vu.ToGojaValue(tt.opts), log.NewNullLogger())
+			err := lo.Parse(vu.Context(), log.NewNullLogger(), vu.ToGojaValue(tt.opts))
 			if tt.err != "" {
 				require.ErrorContains(t, err, tt.err)
 			} else {