Avoid terminal shutdown hang after fatal startup errors

uiterm/ui.go

@@ -5,6 +5,7 @@ import (
 	"strings"
 	"sync"
 	"sync/atomic"
+	"time"
 
 	"github.com/nsf/termbox-go"
 )
@@ -142,7 +143,12 @@ func (ui *Ui) Run(cmds chan string) error {
 	}()
 	defer func() {
 		termbox.Close()
-		<-pollDone
+		// Some termbox backends do not wake PollEvent promptly on Close. A fatal
+		// startup failure must print its stderr error instead of hanging here.
+		select {
+		case <-pollDone:
+		case <-time.After(100 * time.Millisecond):
+		}
 	}()
 
 	ui.manager.OnUiInitialize(ui)