Add Join() from stdlib

.github/workflows/test.yaml

@@ -16,7 +16,7 @@ jobs:
     strategy:
       matrix:
         go-version:
-          - 1.19.x
+          - 1.21.x
         os: [ ubuntu-latest ]
     runs-on: ${{ matrix.os }}
     steps:

errors.go

@@ -97,4 +97,16 @@ func Last(err error, target any) bool {
 	return false
 }
 
+// Join returns an error that wraps the given errors.
+// Any nil error values are discarded.
+// Join returns nil if every value in errs is nil.
+// The error formats as the concatenation of the strings obtained
+// by calling the Error method of each element of errs, with a newline
+// between each string.
+//
+// A non-nil error returned by Join implements the Unwrap() []error method.
+func Join(errs ...error) error {
+	return errors.Join(errs...)
+}
+
 var errorType = reflect.TypeOf((*error)(nil)).Elem()