No declSymbol, no party

src/libs/cplusplus/FindUsages.cpp

@@ -62,8 +62,10 @@ QList<int> FindUsages::operator()(Symbol *symbol, Identifier *id, AST *ast)
     _references.clear();
     _declSymbol = symbol;
     _id = id;
+    if (_declSymbol && _id) {
         _exprDoc = Document::create("<references>");
         accept(ast);
+    }
     return _references;
 }