fix: wrappedError.Is

Is method should return true when used on 2 same errors.

types/errors/errors.go

@@ -318,12 +318,11 @@ func (e *wrappedError) Cause() error {
 
 // Is reports whether any error in e's chain matches a target.
 func (e *wrappedError) Is(target error) bool {
-	if target == nil {
-		return e == target
+	if e == target {
+		return true
 	}
 
 	w := e.Cause()
-
 	for {
 		if w == target {
 			return true

types/errors/errors_test.go

@@ -161,17 +161,24 @@ func (s *errorsTestSuite) TestWrapEmpty() {
 }
 
 func (s *errorsTestSuite) TestWrappedIs() {
+	require := s.Require()
 	err := Wrap(ErrTxTooLarge, "context")
-	s.Require().True(stdlib.Is(err, ErrTxTooLarge))
+	require.True(stdlib.Is(err, ErrTxTooLarge))
 
 	err = Wrap(err, "more context")
-	s.Require().True(stdlib.Is(err, ErrTxTooLarge))
+	require.True(stdlib.Is(err, ErrTxTooLarge))
 
 	err = Wrap(err, "even more context")
-	s.Require().True(stdlib.Is(err, ErrTxTooLarge))
+	require.True(stdlib.Is(err, ErrTxTooLarge))
 
 	err = Wrap(ErrInsufficientFee, "...")
-	s.Require().False(stdlib.Is(err, ErrTxTooLarge))
+	require.False(stdlib.Is(err, ErrTxTooLarge))
+
+	errs := stdlib.New("other")
+	require.True(stdlib.Is(errs, errs))
+
+	errw := &wrappedError{"msg", errs}
+	require.True(errw.Is(errw), "should match itself")
 }
 
 func (s *errorsTestSuite) TestWrappedIsMultiple() {