Fix and improve incorrect error messages (go-gitea#21342)

L

modules/options/static.go

@@ -1,4 +1,4 @@
-// Copyright 2016 The Gitea Authors. All rights reserved.
+// Copyright 2022 The Gitea Authors. All rights reserved.
 // Use of this source code is governed by a MIT-style
 // license that can be found in the LICENSE file.
 
@@ -32,24 +32,23 @@ func Dir(name string) ([]string, error) {
 	customDir := path.Join(setting.CustomPath, "options", name)
 	isDir, err := util.IsDir(customDir)
 	if err != nil {
-		return []string{}, fmt.Errorf("Failed to check if custom directory %s is a directory. %v", err)
+		return []string{}, fmt.Errorf("unable to check if custom directory %q is a directory. %w", customDir, err)
 	}
 	if isDir {
 		files, err := util.StatDir(customDir, true)
 		if err != nil {
-			return []string{}, fmt.Errorf("Failed to read custom directory. %v", err)
+			return []string{}, fmt.Errorf("unable to read custom directory %q. %w", customDir, err)
 		}
 
 		result = append(result, files...)
 	}
 
 	files, err := AssetDir(name)
 	if err != nil {
-		return []string{}, fmt.Errorf("Failed to read embedded directory. %v", err)
+		return []string{}, fmt.Errorf("unable to read embedded directory %q. %w", name, err)
 	}
 
 	result = append(result, files...)
-
 	return directories.AddAndGet(name, result), nil
 }