Add errors.AsError() to get back that behaviour

Author: ConradIrwin

README.md

@@ -66,4 +66,13 @@ everyone can benefit.
 This package is licensed under the MIT license, see LICENSE.MIT for details.
 
 ## Changelog
-* v1.1.0 updated to use go1.13's standard-library errors.Is method instead of == in errors.Is
+* v1.1.0 updated to use go1.13's standard-library errors.Is method instead of == in errors.Is
+* v1.2.0 added `errors.As` from the standard library.
+* v1.3.0 *BREAKING* updated error methods to return `error` instead of `*Error`.
+>  Code that needs access to the underlying `*Error` can use the new errors.AsError(e)
+> ```
+>   // before
+>   errors.New(err).ErrorStack()
+>   // after
+>.  errors.AsError(errors.Wrap(err)).ErrorStack()
+> ```

error.go

@@ -207,3 +207,10 @@ func (err *Error) TypeName() string {
 func (err *Error) Unwrap() error {
 	return err.Err
 }
+
+// AsError converts e to an *errors.Error.
+// If e does not already have a stacktrace attached, the current stack
+// will be added.
+func AsError(e error) *Error {
+	return Wrap(e, 1).(*Error)
+}