protective code for init connection

Author: ysmood

browser.go

@@ -157,6 +157,8 @@ func (b *Browser) Connect() error {
 			return err
 		}
 		b.client = c
+	} else if b.controlURL != "" {
+		panic("Browser.Client and Browser.ControlURL can't be set at the same time")
 	}
 
 	b.initEvents()

browser_test.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/go-rod/rod"
+	"github.com/go-rod/rod/lib/cdp"
 	"github.com/go-rod/rod/lib/devices"
 	"github.com/go-rod/rod/lib/launcher"
 	"github.com/go-rod/rod/lib/proto"
@@ -474,3 +475,10 @@ func TestBrowserLostConnection(t *testing.T) {
 	_, err := p.Eval(`() => new Promise(r => {})`)
 	g.Err(err)
 }
+
+func TestBrowserConnectConflict(t *testing.T) {
+	g := setup(t)
+	g.Panic(func() {
+		rod.New().Client(&cdp.Client{}).ControlURL("test").MustConnect()
+	})
+}