Fix a logic error warning of the type "called C++ object pointer is
null" emitted by Clang Static Analyzer on the following file:
Signed-off-by: Apelete Seketeli <email@example.com>
Attr can never be null here because one of Loc or Block will be non-null. This looks like a deficiency of the static analyzer. I'd rather initialize Attr in each of the branches of the if above if that helps.