add unit test and nil pointer check

Author: GokceGK

internal/cmd/beta/logs/instance/update/update.go

@@ -156,7 +156,11 @@ func outputResult(p *print.Printer, model *inputModel, projectLabel string, inst
 	if instance == nil {
 		return fmt.Errorf("instance is nil")
 	}
-	return p.OutputResult(model.OutputFormat, instance, func() error {
+	var outputFormat string
+	if model.GlobalFlagModel != nil {
+		outputFormat = model.OutputFormat
+	}
+	return p.OutputResult(outputFormat, instance, func() error {
 		p.Outputf("Updated instance %q for project %q.\n", utils.PtrString(instance.DisplayName), projectLabel)
 		return nil
 	})

internal/cmd/beta/logs/instance/update/update_test.go

@@ -267,6 +267,12 @@ func TestOutputResult(t *testing.T) {
 			model:       &inputModel{GlobalFlagModel: &globalflags.GlobalFlagModel{}},
 			wantErr:     false,
 		},
+		{
+			description: "global flag nil",
+			instance:    &logs.LogsInstance{},
+			model:       &inputModel{GlobalFlagModel: nil},
+			wantErr:     false,
+		},
 		{
 			description: "json output",
 			instance:    &logs.LogsInstance{},