Merge pull request #50 from basecamp/fix-ui-crash-on-teardown

Fix UI crash on teardown

Author: monorkin

internal/ui/dashboard.go

@@ -352,6 +352,10 @@ func (m *Dashboard) computeScales() DashboardScales {
 }
 
 func (m *Dashboard) scrollToSelection() {
+	if len(m.panels) == 0 {
+		return
+	}
+
 	panelTop := 0
 	for i := range m.selectedIndex {
 		panelTop += m.panels[i].Height(dashboardShowDetails)

internal/ui/dashboard_test.go

@@ -192,6 +192,23 @@ func TestDashboard_ToggleDetailsEmptyState(t *testing.T) {
 	assert.True(t, dashboardShowDetails) // unchanged — guarded by len(m.apps) > 0
 }
 
+func TestDashboard_SelectPanelAfterAppsRemoved(t *testing.T) {
+	d := testDashboard(3)
+	d.width = 80
+	d.height = 40
+	d.updateViewportSize()
+	d.rebuildViewportContent()
+
+	// Simulate all apps disappearing (e.g. `once teardown` in another shell).
+	d.apps = nil
+	d.buildPanels()
+
+	// Regression: #49 — scrollToSelection used to index into an empty m.panels.
+	assert.NotPanics(t, func() {
+		d.selectPanel(0)
+	})
+}
+
 func TestDashboard_EmptyStateShowsMessage(t *testing.T) {
 	d := testDashboard(0)
 	d, _ = updateDashboard(d, tea.WindowSizeMsg{Width: 80, Height: 24})