.: fix a few bugs (#961)

internal/engine/upper.go

@@ -400,6 +400,10 @@ func handleConfigsReloaded(
 		Reason:     model.BuildReasonFlagConfig,
 	}
 	setLastTiltfileBuild(state, status)
+	if event.Err != nil {
+		// There was an error, so don't update status with the new, nonexistent state
+		return
+	}
 
 	newDefOrder := make([]model.ManifestName, len(manifests))
 	for i, m := range manifests {

internal/hud/hud.go

@@ -194,7 +194,9 @@ func (h *Hud) handleScreenEvent(ctx context.Context, dispatch func(action store.
 			am := h.activeModal()
 			if am == nil {
 				selectedIdx, r := h.selectedResource()
-
+				if selectedIdx == 0 {
+					break
+				}
 				if r.IsYAML() {
 					h.currentViewState.AlertMessage = fmt.Sprintf("YAML Resources don't have logs")
 					break

internal/model/globalyaml.go

@@ -1,7 +1,7 @@
 package model
 
 // TODO(maia): throw an error if you try to name a manifest this in your Tiltfile?
-const GlobalYAMLManifestName = ManifestName("GlobalYAML")
+const GlobalYAMLManifestName = ManifestName("k8s_yaml")
 
 type YAMLManifest struct {
 	name    ManifestName

internal/rty/scroll.go

@@ -408,13 +408,22 @@ func adjustElementScroll(prevInt interface{}, newChildren []string) (*ElementScr
 	next := &clone
 	next.children = newChildren
 
+	if len(newChildren) == 0 {
+		next.elementIdx = 0
+		return next, ""
+	}
 	if len(prev.children) == 0 {
 		sel := ""
 		if len(next.children) > 0 {
 			sel = next.children[0]
 		}
 		return next, sel
 	}
+	if prev.elementIdx >= len(prev.children) {
+		// NB(dbentley): this should be impossible, but we were hitting it and it was crashing
+		next.elementIdx = 0
+		return next, ""
+	}
 	prevChild := prev.children[prev.elementIdx]
 	for i, child := range newChildren {
 		if child == prevChild {