Disable staging all files when there are none to stage (#5932)

Pressing `a` in the files panel to stage all files would show a
confusing error popup about something with submodules, which made no
sense at all. And worse, when pressing `a` very quickly after startup
(before the initial refresh had a chance to populate the files panel) it
would crash with a nil pointer panic.

Fix both by showing an error toast that there are no files to stage.

Fixes #5929.

pkg/gui/controllers/files_controller.go

@@ -130,10 +130,11 @@ func (self *FilesController) GetKeybindings(opts types.KeybindingsOpts) []*types
 			OpensMenu:   true,
 		},
 		{
-			Keys:        opts.GetKeys(opts.Config.Files.ToggleStagedAll),
-			Handler:     self.toggleStagedAll,
-			Description: self.c.Tr.ToggleStagedAll,
-			Tooltip:     self.c.Tr.ToggleStagedAllTooltip,
+			Keys:              opts.GetKeys(opts.Config.Files.ToggleStagedAll),
+			Handler:           self.toggleStagedAll,
+			GetDisabledReason: self.require(self.anyFilesDisplayed),
+			Description:       self.c.Tr.ToggleStagedAll,
+			Tooltip:           self.c.Tr.ToggleStagedAllTooltip,
 		},
 		{
 			Keys:              opts.GetKeys(opts.Config.Universal.GoInto),
@@ -916,6 +917,17 @@ func (self *FilesController) openSubmoduleConflictMenu(file *models.File) error
 	})
 }
 
+// The stage-all command acts on the file tree as it is displayed, so there has
+// to be something in it. This is also the case before the first files refresh
+// has come in, when there is no tree at all yet.
+func (self *FilesController) anyFilesDisplayed() *types.DisabledReason {
+	if self.context().FileTreeViewModel.Len() == 0 {
+		return &types.DisabledReason{Text: self.c.Tr.NoChangedFiles}
+	}
+
+	return nil
+}
+
 func (self *FilesController) toggleStagedAll() error {
 	if err := self.toggleStagedAllWithLock(); err != nil {
 		return err

pkg/integration/tests/file/stage_all_without_changed_files.go

@@ -0,0 +1,25 @@
+package file
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var StageAllWithoutChangedFiles = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Pressing the stage-all key when there are no changed files says that there are none",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig:  func(config *config.AppConfig) {},
+	SetupRepo: func(shell *Shell) {
+		shell.EmptyCommit("first commit")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Files().
+			IsFocused().
+			IsEmpty().
+			Press(keys.Files.ToggleStagedAll).
+			Tap(func() {
+				t.ExpectToast(Contains("No changed files"))
+			})
+	},
+})

pkg/integration/tests/test_list.go

@@ -248,6 +248,7 @@ var tests = []*components.IntegrationTest{
 	file.RenameSimilarityThresholdChange,
 	file.RenamedFiles,
 	file.RenamedFilesNoRootItem,
+	file.StageAllWithoutChangedFiles,
 	file.StageChildrenRangeSelect,
 	file.StageDeletedRangeSelect,
 	file.StageRangeSelect,