Simplify error handling (#3502)

- **PR Description**

Simplify and canonicalize error handling across the code base.

Previously it was important to make sure that errors don't bubble up
into gocui, because it would panic there; so we had to show errors in
error panels in the right places (in controller code, usually). This is
error-prone because it's easy to forget (see #3490 for an example);
also, it's not always obvious where in the call chain the error panel
needs to be shown. Most of the time it's in controller code, but we had
plenty of calls to `Error()` in helpers, and I remember that I found
this very confusing when I was new to the code base.

Change this so that you can simply return errors everywhere. The
functions to show an error message manually have been removed for
clarity.

I tried to structure the commits so that you can review them one by one.

Closes #3491.

1 files changed, 7 insertions, 12 deletions

diff --git a/pkg/gui/controllers/undo_controller.go b/pkg/gui/controllers/undo_controller.go
index 2df3b8689..96e9f3f11 100644
--- a/pkg/gui/controllers/undo_controller.go
+++ b/pkg/gui/controllers/undo_controller.go
@@ -1,6 +1,7 @@
 package controllers
 
 import (
+	"errors"
 	"fmt"
 
 	"github.com/jesseduffield/gocui"
@@ -78,7 +79,7 @@ func (self *UndoController) reflogUndo() error {
 	undoingStatus := self.c.Tr.UndoingStatus
 
 	if self.c.Git().Status.WorkingTreeState() == enums.REBASE_MODE_REBASING {
-		return self.c.ErrorMsg(self.c.Tr.CantUndoWhileRebasing)
+		return errors.New(self.c.Tr.CantUndoWhileRebasing)
 	}
 
 	return self.parseReflogForActions(func(counter int, action reflogAction) (bool, error) {
@@ -126,7 +127,7 @@ func (self *UndoController) reflogRedo() error {
 	redoingStatus := self.c.Tr.RedoingStatus
 
 	if self.c.Git().Status.WorkingTreeState() == enums.REBASE_MODE_REBASING {
-		return self.c.ErrorMsg(self.c.Tr.CantRedoWhileRebasing)
+		return errors.New(self.c.Tr.CantRedoWhileRebasing)
 	}
 
 	return self.parseReflogForActions(func(counter int, action reflogAction) (bool, error) {
@@ -234,10 +235,7 @@ type hardResetOptions struct {
 // only to be used in the undo flow for now (does an autostash)
 func (self *UndoController) hardResetWithAutoStash(commitHash string, options hardResetOptions) error {
 	reset := func() error {
-		if err := self.c.Helpers().Refs.ResetToRef(commitHash, "hard", options.EnvVars); err != nil {
-			return self.c.Error(err)
-		}
-		return nil
+		return self.c.Helpers().Refs.ResetToRef(commitHash, "hard", options.EnvVars)
 	}
 
 	// if we have any modified tracked files we need to ask the user if they want us to stash for them
@@ -250,20 +248,17 @@ func (self *UndoController) hardResetWithAutoStash(commitHash string, options ha
 			HandleConfirm: func() error {
 				return self.c.WithWaitingStatus(options.WaitingStatus, func(gocui.Task) error {
 					if err := self.c.Git().Stash.Push(self.c.Tr.StashPrefix + commitHash); err != nil {
-						return self.c.Error(err)
+						return err
 					}
 					if err := reset(); err != nil {
 						return err
 					}
 
 					err := self.c.Git().Stash.Pop(0)
-					if err := self.c.Refresh(types.RefreshOptions{}); err != nil {
-						return err
-					}
 					if err != nil {
-						return self.c.Error(err)
+						return err
 					}
-					return nil
+					return self.c.Refresh(types.RefreshOptions{})
 				})
 			},
 		})