fix(config): standardize config key errors

Author: Peter Steinberger

internal/config/keys.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"errors"
 	"fmt"
 	"strings"
 	"time"
@@ -64,6 +65,12 @@ var keySpecs = map[Key]KeySpec{
 	},
 }
 
+var (
+	errUnknownConfigKey     = errors.New("unknown config key")
+	errConfigKeyCannotSet   = errors.New("config key cannot be set")
+	errConfigKeyCannotUnset = errors.New("config key cannot be unset")
+)
+
 func (k Key) String() string {
 	return string(k)
 }
@@ -72,27 +79,31 @@ func (k Key) Validate() error {
 	if _, ok := keySpecs[k]; ok {
 		return nil
 	}
-	return fmt.Errorf("unknown config key: %s (valid keys: %s)", k, strings.Join(KeyNames(), ", "))
+
+	return fmt.Errorf("%w: %s (valid keys: %s)", errUnknownConfigKey, k, strings.Join(KeyNames(), ", "))
 }
 
 func ParseKey(raw string) (Key, error) {
 	key := Key(raw)
 	if err := key.Validate(); err != nil {
 		return "", err
 	}
+
 	return key, nil
 }
 
 func KeySpecFor(key Key) (KeySpec, error) {
 	if err := key.Validate(); err != nil {
 		return KeySpec{}, err
 	}
+
 	return keySpecs[key], nil
 }
 
 func KeyList() []Key {
 	keys := make([]Key, len(keyOrder))
 	copy(keys, keyOrder)
+
 	return keys
 }
 
@@ -101,6 +112,7 @@ func KeyNames() []string {
 	for _, key := range keyOrder {
 		names = append(names, key.String())
 	}
+
 	return names
 }
 
@@ -109,26 +121,31 @@ func GetValue(cfg File, key Key) string {
 	if !ok || spec.Get == nil {
 		return ""
 	}
+
 	return spec.Get(cfg)
 }
 
 func SetValue(cfg *File, key Key, value string) error {
 	if err := key.Validate(); err != nil {
 		return err
 	}
+
 	if spec := keySpecs[key]; spec.Set != nil {
 		return spec.Set(cfg, value)
 	}
-	return fmt.Errorf("config key %s cannot be set", key)
+
+	return fmt.Errorf("%w: %s", errConfigKeyCannotSet, key)
 }
 
 func UnsetValue(cfg *File, key Key) error {
 	if err := key.Validate(); err != nil {
 		return err
 	}
+
 	if spec := keySpecs[key]; spec.Unset != nil {
 		spec.Unset(cfg)
 		return nil
 	}
-	return fmt.Errorf("config key %s cannot be unset", key)
+
+	return fmt.Errorf("%w: %s", errConfigKeyCannotUnset, key)
 }