#vulnerable code 
                                @Override
    public SymbolReference<? extends ValueDeclaration> solveSymbol(String name, TypeSolver typeSolver) {
        if (wrappedNode.getFieldExpr().toString().equals(name)) {
            if (wrappedNode.getScope() instanceof ThisExpr) {
                Type typeOfThis = JavaParserFacade.get(typeSolver).getTypeOfThisIn(wrappedNode);
                return new SymbolSolver(typeSolver).solveSymbolInType(typeOfThis.asReferenceType().getTypeDeclaration(), name);
            }
        }
        return JavaParserFactory.getContext(wrappedNode.getParentNode(), typeSolver).solveSymbol(name, typeSolver);
    } 
                            #location 9 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    public SymbolReference<? extends ValueDeclaration> solveSymbol(String name, TypeSolver typeSolver) {
        if (wrappedNode.getFieldExpr().toString().equals(name)) {
            if (wrappedNode.getScope() instanceof ThisExpr) {
                Type typeOfThis = JavaParserFacade.get(typeSolver).getTypeOfThisIn(wrappedNode);
                return new SymbolSolver(typeSolver).solveSymbolInType(typeOfThis.asReferenceType().getTypeDeclaration(), name);
            }
        }
        return JavaParserFactory.getContext(getParentNode(wrappedNode), typeSolver).solveSymbol(name, typeSolver);
    }