✨ Refactor: Convert WaitErr to an interface and add New constructor

waiterr.go

@@ -5,23 +5,43 @@ import (
 	"sync"
 )
 
+func New() WaitErr {
+	var we waitErr
+	we.errCh = make(chan error, 1)
+
+	return &we
+}
+
+// WaitErr provides a way to run multiple goroutines and wait for their completion,
+// collecting any errors they return.
+type WaitErr interface {
+	// Go runs f in its own goroutine. When f returns, its error is stored, and returned
+	// with [WaitErr.Wait].
+	Go(f func() error)
+	// WaitForError waits for the first error to be returned by one of our go routines, and immediately returns
+	// with that error. If all functions return successfully, a nil is returned.
+	WaitForError() error
+	// Wait for all current goroutines to finish. Return an error that combines all errors returned
+	// in the group so far (if any).
+	Wait() error
+	// Unwrap returns all non-nil errors returned by our functions.
+	// If no errors were returned, or all errors are nil, it returns nil.
+	Unwrap() []error
+}
+
 // WaitErr wraps a [sync.WaitGroup] with error handling.
-type WaitErr struct {
-	wg            sync.WaitGroup
-	errs          []error
-	mut           sync.RWMutex
-	firstErr      error
-	firstErrOnce  sync.Once
-	errCh         chan error // Buffered channel of size 1
-	initErrChOnce sync.Once
+type waitErr struct {
+	wg           sync.WaitGroup
+	errs         []error
+	mut          sync.RWMutex
+	firstErr     error
+	firstErrOnce sync.Once
+	errCh        chan error // Buffered channel of size 1
 }
 
 // Go runs f in its own goroutine. When f returns, its error is stored, and returned
 // with [WaitErr.Wait].
-func (we *WaitErr) Go(f func() error) {
-	we.initErrChOnce.Do(func() {
-		we.errCh = make(chan error, 1)
-	})
+func (we *waitErr) Go(f func() error) {
 	wrap := func() {
 		err := f()
 
@@ -48,10 +68,7 @@ func (we *WaitErr) Go(f func() error) {
 
 // WaitForError waits for the first error to be returned by one of our go routines, and immediately returns
 // with that error. If all functions return successfully, a nil is returned. It will panic if called before Go.
-func (we *WaitErr) WaitForError() error {
-	if we.errCh == nil {
-		panic("WaitForError called before Go")
-	}
+func (we *waitErr) WaitForError() error {
 	// Check if an error has already been set
 	we.mut.RLock()
 	if we.firstErr != nil {
@@ -82,7 +99,7 @@ func (we *WaitErr) WaitForError() error {
 
 // Wait for all current goroutines to finish. Return an error that combines all errors returned
 // in the group so far (if any).
-func (we *WaitErr) Wait() error {
+func (we *waitErr) Wait() error {
 	we.wg.Wait()
 	we.mut.RLock()
 	defer we.mut.RUnlock()
@@ -91,7 +108,7 @@ func (we *WaitErr) Wait() error {
 
 // Unwrap returns all non-nil errors returned by our functions.
 // If no errors were returned, or all errors are nil, it returns nil.
-func (we *WaitErr) Unwrap() []error {
+func (we *waitErr) Unwrap() []error {
 	errs := make([]error, 0, len(we.errs))
 	for _, e := range we.errs {
 		if e != nil {