Fixes following error on macOS:
```
CHECK-NEXT: (llvm::SmallVector<int, 2>) value = size=2 {
^
<stdin>:41:65: note: scanning from here
(llvm::Expected<llvm::SmallVector<int, 2> &>) ExpectedVecRef = {
^
<stdin>:42:31: note: possible intended match here
(std::__1::reference_wrapper<llvm::SmallVector<int, 2> >::type) value = size=2 {
```