fix: passing ResultError to Error thru operator<<

It is typical to pass error to callers like following;

    if (!result) {
      return Error() << result.error();
    }

To transfer errno(or ResultError#code()), Error defines a specialization
operator<<(const ResultError&).

This change fixes so that ResultError is properly handled

Bug: 132145659
Test: atest libbase_test
Change-Id: Ib35457da2d4b923d8e652c54ac510a75546cf918
diff --git a/base/result_test.cpp b/base/result_test.cpp
index 72f97f4..e864b97 100644
--- a/base/result_test.cpp
+++ b/base/result_test.cpp
@@ -143,8 +143,8 @@
   ASSERT_FALSE(result2);
   ASSERT_FALSE(result2.has_value());
 
-  EXPECT_EQ(0, result.error().code());
-  EXPECT_EQ(error_text, result.error().message());
+  EXPECT_EQ(0, result2.error().code());
+  EXPECT_EQ(error_text, result2.error().message());
 }
 
 TEST(result, result_error_through_ostream) {
@@ -159,8 +159,8 @@
   ASSERT_FALSE(result2);
   ASSERT_FALSE(result2.has_value());
 
-  EXPECT_EQ(0, result.error().code());
-  EXPECT_EQ(error_text, result.error().message());
+  EXPECT_EQ(0, result2.error().code());
+  EXPECT_EQ(error_text, result2.error().message());
 }
 
 TEST(result, result_errno_error_through_ostream) {
@@ -179,8 +179,8 @@
   ASSERT_FALSE(result2);
   ASSERT_FALSE(result2.has_value());
 
-  EXPECT_EQ(test_errno, result.error().code());
-  EXPECT_EQ(error_text + ": " + strerror(test_errno), result.error().message());
+  EXPECT_EQ(test_errno, result2.error().code());
+  EXPECT_EQ(error_text + ": " + strerror(test_errno), result2.error().message());
 }
 
 TEST(result, constructor_forwarding) {