lock: cleanup error message

The error message is now `Fatal: unable to create lock in backend:
[...]` instead of `unable to create lock in backend: Fatal: [...]`.

cmd/restic/lock.go

@@ -2,11 +2,11 @@ package main
 
 import (
 	"context"
-	"fmt"
 	"sync"
 	"time"
 
 	"github.com/restic/restic/internal/debug"
+	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/restic"
 )
 
@@ -45,7 +45,7 @@ func lockRepository(ctx context.Context, repo restic.Repository, exclusive bool)
 
 	lock, err := lockFn(ctx, repo)
 	if err != nil {
-		return nil, ctx, fmt.Errorf("unable to create lock in backend: %w", err)
+		return nil, ctx, errors.Fatalf("unable to create lock in backend: %v", err)
 	}
 	debug.Log("create lock %p (exclusive %v)", lock, exclusive)
 

internal/restic/lock.go

@@ -146,7 +146,7 @@ func (l *Lock) checkForOtherLocks(ctx context.Context) error {
 				// if we cannot load a lock then it is unclear whether it can be ignored
 				// it could either be invalid or just unreadable due to network/permission problems
 				debug.Log("ignore lock %v: %v", id, err)
-				return errors.Fatal(err.Error())
+				return err
 			}
 
 			if l.Exclusive {