fix deserialization panics on empty map

internal/error/error_test.go

@@ -18,11 +18,11 @@ func TestBaseWithSubject(t *testing.T) {
 	withSubjectf := err.Subjectf("%s %s", "foo", "bar")
 
 	ExpectError(t, err, withSubject)
-	ExpectStrEqual(t, withSubject.Error(), "foo: error")
+	ExpectEqual(t, withSubject.Error(), "foo: error")
 	ExpectTrue(t, withSubject.Is(err))
 
 	ExpectError(t, err, withSubjectf)
-	ExpectStrEqual(t, withSubjectf.Error(), "foo bar: error")
+	ExpectEqual(t, withSubjectf.Error(), "foo bar: error")
 	ExpectTrue(t, withSubjectf.Is(err))
 }
 
@@ -114,9 +114,9 @@ func TestErrorWith(t *testing.T) {
 func TestErrorStringSimple(t *testing.T) {
 	errFailure := New("generic failure")
 	ne := errFailure.Subject("foo bar")
-	ExpectStrEqual(t, ne.Error(), "foo bar: generic failure")
+	ExpectEqual(t, ne.Error(), "foo bar: generic failure")
 	ne = ne.Subject("baz")
-	ExpectStrEqual(t, ne.Error(), "baz > foo bar: generic failure")
+	ExpectEqual(t, ne.Error(), "baz > foo bar: generic failure")
 }
 
 func TestErrorStringNested(t *testing.T) {
@@ -153,5 +153,5 @@ func TestErrorStringNested(t *testing.T) {
       • action 3 > inner3: generic failure
         • 3
         • 3`
-	ExpectStrEqual(t, ne.Error(), want)
+	ExpectEqual(t, ne.Error(), want)
 }

internal/error/utils.go

@@ -1,7 +1,6 @@
 package err
 
 import (
-	"errors"
 	"fmt"
 )
 
@@ -20,12 +19,16 @@ func Errorf(format string, args ...any) Error {
 	return &baseError{fmt.Errorf(format, args...)}
 }
 
-func From(err error) (e Error) {
+func From(err error) Error {
 	if err == nil {
 		return nil
 	}
-	if errors.As(err, &e) {
-		return e
+	//nolint:errorlint
+	switch err := err.(type) {
+	case *baseError:
+		return err
+	case *nestedError:
+		return err
 	}
 	return &baseError{err}
 }