[llvm] Unittest for Error forwarding, follow-up to PR #92208 (PR #92314)

[Mircea Trofin via llvm-commits]

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@@ -1172,6 +1173,7 @@ TEST(Error, ForwardToExpected) {
   };
   std::optional<int> MaybeV;
   EXPECT_THAT_ERROR(ExpectedReturningFct(true).moveInto(MaybeV), Failed());
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mtrofin wrote:

Error->Error forwarding worked. Error->Expected<T> didn't (if I understand your question right)

https://github.com/llvm/llvm-project/pull/92314