errors: rewrite errors to follow go best practices

Errors should not start capitalised and they should not contain the word error
or state that they "failed" as we already know it is an error

Signed-off-by: Kristoffer Dalby <kristoffer@dalby.cc>

hscontrol/db/preauth_keys.go

@@ -139,7 +139,7 @@ func CreatePreAuthKey(
 	}
 
 	if err := tx.Save(&key).Error; err != nil {
-		return nil, fmt.Errorf("failed to create key in the database: %w", err)
+		return nil, fmt.Errorf("creating key in database: %w", err)
 	}
 
 	return &types.PreAuthKeyNew{
@@ -296,7 +296,7 @@ func DestroyPreAuthKey(tx *gorm.DB, id uint64) error {
 			Where("auth_key_id = ?", id).
 			Update("auth_key_id", nil).Error
 		if err != nil {
-			return fmt.Errorf("failed to clear auth_key_id on nodes: %w", err)
+			return fmt.Errorf("clearing auth_key_id on nodes: %w", err)
 		}
 
 		// Then delete the pre-auth key
@@ -325,7 +325,7 @@ func (hsdb *HSDatabase) DeletePreAuthKey(id uint64) error {
 func UsePreAuthKey(tx *gorm.DB, k *types.PreAuthKey) error {
 	err := tx.Model(k).Update("used", true).Error
 	if err != nil {
-		return fmt.Errorf("failed to update key used status in the database: %w", err)
+		return fmt.Errorf("updating key used status in database: %w", err)
 	}
 
 	k.Used = true