Fix golangci-lint issues

Address gocritic, revive, and unused-code findings in the Pipe/runner helper code.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: znull

pipe/config.go

@@ -33,15 +33,15 @@ func NewConfig(options ...ConfigOption) *Config {
 // plus the additional `option`.
 func (cfg *Config) WithOption(option ConfigOption) *Config {
 	newCfg := newConfig(cfg.options, 1)
-	newCfg.options = append(cfg.options, option)
+	newCfg.options = append(newCfg.options, option)
 	return newCfg
 }
 
 // WithOption returns a new `Config` with the same options as `cfg`
 // plus the additional `options`.
 func (cfg *Config) WithOptions(options ...ConfigOption) *Config {
 	newCfg := newConfig(cfg.options, len(options))
-	newCfg.options = append(cfg.options, options...)
+	newCfg.options = append(newCfg.options, options...)
 	return newCfg
 }
 

pipe/event_error.go

@@ -16,9 +16,8 @@ type EventHandler func(err *EventError)
 func (err *EventError) Error() string {
 	if err.Msg == "" {
 		return fmt.Sprintf("%s: %v", err.Command, err.Err)
-	} else {
-		return fmt.Sprintf("%s in stage %q: %v", err.Msg, err.Command, err.Err)
 	}
+	return fmt.Sprintf("%s in stage %q: %v", err.Msg, err.Command, err.Err)
 }
 
 func (err *EventError) Unwrap() error {

pipe/options.go

@@ -13,16 +13,6 @@ type ConfigOption interface {
 	Option
 }
 
-// sliceConfigOption is a `ConfigOption` based on a slice of other
-// `ConfigOption`s.
-type sliceConfigOption []ConfigOption
-
-func (sco sliceConfigOption) apply(r *runner) {
-	for _, opt := range sco {
-		opt.apply(r)
-	}
-}
-
 // funcConfigOption implements `ConfigOption` by calling a function.
 type funcConfigOption struct {
 	fn func(r *runner)