mobile: Bug fix: error must be received without waiting for renderCh

Even when error happens, the error was not received when renderCh
received. This was the cause of freezing when error happens.

internal/graphicsdriver/opengl/context_mobile.go

@@ -73,7 +73,7 @@ type contextImpl struct {
 	worker mgl.Worker
 }
 
-func (c *context) doWork(chError <-chan error, chDone <-chan struct{}) error {
+func (c *context) doWork(chDone <-chan struct{}) error {
 	if c.worker == nil {
 		panic("not reached")
 	}
@@ -82,8 +82,6 @@ func (c *context) doWork(chError <-chan error, chDone <-chan struct{}) error {
 loop:
 	for {
 		select {
-		case err := <-chError:
-			return err
 		case <-workAvailable:
 			c.worker.DoWork()
 		case <-chDone:

internal/graphicsdriver/opengl/driver_mobile.go

@@ -20,8 +20,8 @@ import (
 	"golang.org/x/mobile/gl"
 )
 
-func (d *Driver) DoWork(chError <-chan error, chDone <-chan struct{}) error {
-	return d.context.doWork(chError, chDone)
+func (d *Driver) DoWork(chDone <-chan struct{}) error {
+	return d.context.doWork(chDone)
 }
 
 func (d *Driver) Init() {

internal/ui/ui_mobile.go

@@ -52,8 +52,10 @@ func Render(chError <-chan error) error {
 	}
 	// TODO: Check this is called on the rendering thread
 	select {
+	case err := <-chError:
+		return err
 	case renderCh <- struct{}{}:
-		return opengl.Get().DoWork(chError, renderChEnd)
+		return opengl.Get().DoWork(renderChEnd)
 	case <-time.After(500 * time.Millisecond):
 		// This function must not be blocked. We need to break for timeout.
 		return nil