fix issues TUI display reliability

cmd/issues-tui/tui.go

@@ -25,6 +25,9 @@ type model struct {
 	sc   *scanner
 	cfg  modelConfig
 	snap snapshot
+	// scanErr is kept separately so a failed refresh does not erase the last
+	// successful data from the display.
+	scanErr error
 
 	scanning   bool
 	nextScanAt time.Time
@@ -79,7 +82,13 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		return m, cmd
 
 	case snapshotMsg:
-		m.snap = snapshot(msg)
+		snap := snapshot(msg)
+		if snap.Err != nil {
+			m.scanErr = snap.Err
+		} else {
+			m.snap = snap
+			m.scanErr = nil
+		}
 		m.scanning = false
 		m.nextScanAt = time.Now().Add(m.cfg.Interval)
 		return m, nil
@@ -90,6 +99,6 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 func (m model) View() string {
 	return renderSnapshot(m.snap, snapshotOptions{
 		Width: m.width, Height: m.height, Title: m.cfg.Title, BaseURL: m.cfg.BaseURL,
-		Scanning: m.scanning, NextScanAt: m.nextScanAt, Now: time.Now(),
+		Scanning: m.scanning, NextScanAt: m.nextScanAt, Now: time.Now(), ScanError: m.scanErr,
 	})
 }