Add Merge to ierrors

ierrors/ierrors_no_stacktrace.go

@@ -19,6 +19,29 @@ func Join(errs ...error) error {
 	return errors.Join(errs...)
 }
 
+// Merge merges multiple errors into a single error by wrapping them.
+// Any nil error values are discarded.
+// Merge returns nil if every value in errs is nil.
+// Merge adds a stacktrace to the error if there was no stacktrace
+// in the error tree yet and if the build flag "stacktrace" is set.
+func Merge(errs ...error) error {
+	var result error
+	for _, err := range errs {
+		if err == nil {
+			continue
+		}
+
+		if result == nil {
+			result = err
+			continue
+		}
+
+		result = fmt.Errorf("%w: %w", result, err)
+	}
+
+	return result
+}
+
 // Errorf formats according to a format specifier and returns the string as a
 // value that satisfies error.
 //

ierrors/ierrors_stacktrace.go

@@ -58,6 +58,10 @@ func newErrorWithStacktrace(err error, stacktrace string) *errorWithStacktrace {
 // if yes, it simply returns the err.
 // if not, it returns a new error with a stacktrace appended.
 func ensureStacktraceUniqueness(err error) error {
+	if err == nil {
+		return nil
+	}
+
 	var errWithStacktrace *errorWithStacktrace
 	if errors.As(err, &errWithStacktrace) {
 		return err
@@ -78,6 +82,29 @@ func Join(errs ...error) error {
 	return ensureStacktraceUniqueness(errors.Join(errs...))
 }
 
+// Merge merges multiple errors into a single error by wrapping them.
+// Any nil error values are discarded.
+// Merge returns nil if every value in errs is nil.
+// Merge adds a stacktrace to the error if there was no stacktrace
+// in the error tree yet and if the build flag "stacktrace" is set.
+func Merge(errs ...error) error {
+	var result error
+	for _, err := range errs {
+		if err == nil {
+			continue
+		}
+
+		if result == nil {
+			result = err
+			continue
+		}
+
+		result = fmt.Errorf("%w: %w", result, err)
+	}
+
+	return ensureStacktraceUniqueness(result)
+}
+
 // Errorf formats according to a format specifier and returns the string as a
 // value that satisfies error.
 //

ierrors/ierrors_stacktrace_test.go

@@ -63,4 +63,7 @@ func TestErrors(t *testing.T) {
 
 	err15 := WithStack(errStacktrace)
 	require.Equal(t, 1, strings.Count(err15.Error(), "github.com/iotaledger/hive.go/ierrors.TestErrors"))
+
+	err16 := Merge(New("err16"), New("merged"))
+	require.Equal(t, 1, strings.Count(err16.Error(), "github.com/iotaledger/hive.go/ierrors.TestErrors"))
 }