Prevent at compile time converting from Error::success() to Expected<T>

This would trigger an assertion at runtime otherwise.

Differential Revision: https://reviews.llvm.org/D26482

llvm-svn: 286562
diff --git a/lld/lib/Core/Resolver.cpp b/lld/lib/Core/Resolver.cpp
index ef694fd..e7cfaaa 100644
--- a/lld/lib/Core/Resolver.cpp
+++ b/lld/lib/Core/Resolver.cpp
@@ -100,7 +100,7 @@
 
   if (auto ec = undefAddedOrError.takeError())
     return ec;
-  return llvm::Error();
+  return llvm::Error::success();
 }
 
 bool Resolver::doUndefinedAtom(OwningAtomPtr<UndefinedAtom> atom) {