Improve console input EOF handling

Related to #126. Need some Windows tester to tell me how it works.

m/pager.go

@@ -422,6 +422,12 @@ func (p *Pager) StartPaging(screen twin.Screen) {
 	log.Trace("Pager starting")
 	defer log.Trace("Pager done")
 
+	defer func() {
+		if p.reader.err != nil {
+			log.Warnf("Reader reported an error: %s", p.reader.err.Error())
+		}
+	}()
+
 	unprintableStyle = p.UnprintableStyle
 	ConsumeLessTermcapEnvs()
 
@@ -528,6 +534,10 @@ func (p *Pager) StartPaging(screen twin.Screen) {
 		case twin.EventResize:
 			// We'll be implicitly redrawn just by taking another lap in the loop
 
+		case twin.EventExit:
+			log.Debug("Got a Twin exit event, exiting")
+			return
+
 		case eventMoreLinesAvailable:
 			if p.mode.isViewing() && p.Following {
 				p.scrollToEnd()
@@ -544,10 +554,6 @@ func (p *Pager) StartPaging(screen twin.Screen) {
 			log.Warnf("Unhandled event type: %v", event)
 		}
 	}
-
-	if p.reader.err != nil {
-		log.Warnf("Reader reported an error: %s", p.reader.err.Error())
-	}
 }
 
 // After the pager has exited and the normal screen has been restored, you can

twin/events.go

@@ -30,6 +30,14 @@ type EventResize struct {
 	// This interface intentionally left blank
 }
 
+// If we're unable to continue showing the screen, we'll send this event and
+// drop out.
+//
+// Ref: https://github.com/walles/moar/issues/126
+type EventExit struct {
+	// This interface intentionally left blank
+}
+
 func (eventRune *EventRune) Rune() rune {
 	return eventRune.rune
 }

twin/screen.go

@@ -2,7 +2,9 @@
 package twin
 
 import (
+	"errors"
 	"fmt"
+	"io"
 	"os"
 	"regexp"
 	"strings"
@@ -206,6 +208,14 @@ func (screen *UnixScreen) mainLoop() {
 	for {
 		count, err := screen.ttyIn.Read(buffer)
 		if err != nil {
+			if errors.Is(err, io.EOF) {
+				// This happens when the terminal window is closed
+				var event Event = EventExit{}
+				screen.events <- event
+				return
+			}
+
+			// Unknown error
 			panic(err)
 		}