#vulnerable code 
                                @Override
    public void executeTask(IConversationMemory memory) {
        IData<String> expressionsData = memory.getCurrentStep().getLatestData(EXPRESSIONS_PARSED_IDENTIFIER);
        List<IData<Context>> contextDataList = memory.getCurrentStep().getAllData(CONTEXT_IDENTIFIER);

        if (expressionsData == null && contextDataList == null) {
            return;
        }

        List<Expression> aggregatedExpressions = new LinkedList<>();

        if (contextDataList != null) {
            aggregatedExpressions.addAll(extractContextProperties(contextDataList));
        }

        if (expressionsData != null) {
            aggregatedExpressions.addAll(expressionProvider.parseExpressions(expressionsData.getResult()));
        }

        List<PropertyEntry> properties = propertyDisposer.extractProperties(aggregatedExpressions);

        // see if action "CATCH_ANY_INPUT_AS_PROPERTY" was in the last step, so we take last user input into account
        IConversationStepStack previousSteps = memory.getPreviousSteps();
        if (previousSteps.size() > 0) {
            IData<List<String>> actionsData = previousSteps.get(0).getLatestData(ACTIONS_IDENTIFIER);
            List<String> actions = actionsData.getResult();
            if (actions != null && actions.contains(CATCH_ANY_INPUT_AS_PROPERTY_ACTION)) {
                IData<String> initialInputData = memory.getCurrentStep().getLatestData(INPUT_INITIAL_IDENTIFIER);
                String initialInput = initialInputData.getResult();
                if (!initialInput.isEmpty()) {
                    properties.add(new PropertyEntry(Collections.singletonList(EXPRESSION_MEANING_USER_INPUT), initialInput));
                }
            }
        }

        if (!properties.isEmpty()) {
            memory.getCurrentStep().storeData(dataFactory.createData(PROPERTIES_EXTRACTED_IDENTIFIER, properties, true));
        }
    } 
                            #location 26 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    public void executeTask(IConversationMemory memory) {
        IData<String> expressionsData = memory.getCurrentStep().getLatestData(EXPRESSIONS_PARSED_IDENTIFIER);
        List<IData<Context>> contextDataList = memory.getCurrentStep().getAllData(CONTEXT_IDENTIFIER);

        if (expressionsData == null && contextDataList == null) {
            return;
        }

        List<Expression> aggregatedExpressions = new LinkedList<>();

        if (contextDataList != null) {
            aggregatedExpressions.addAll(extractContextProperties(contextDataList));
        }

        if (expressionsData != null) {
            aggregatedExpressions.addAll(expressionProvider.parseExpressions(expressionsData.getResult()));
        }

        List<PropertyEntry> properties = propertyDisposer.extractProperties(aggregatedExpressions);

        // see if action "CATCH_ANY_INPUT_AS_PROPERTY" was in the last step, so we take last user input into account
        IConversationStepStack previousSteps = memory.getPreviousSteps();
        if (previousSteps.size() > 0) {
            IData<List<String>> actionsData = previousSteps.get(0).getLatestData(ACTIONS_IDENTIFIER);
            if (actionsData != null) {
                List<String> actions = actionsData.getResult();
                if (actions != null && actions.contains(CATCH_ANY_INPUT_AS_PROPERTY_ACTION)) {
                    IData<String> initialInputData = memory.getCurrentStep().getLatestData(INPUT_INITIAL_IDENTIFIER);
                    String initialInput = initialInputData.getResult();
                    if (!initialInput.isEmpty()) {
                        properties.add(new PropertyEntry(
                                Collections.singletonList(EXPRESSION_MEANING_USER_INPUT), initialInput));
                    }
                }
            }
        }

        if (!properties.isEmpty()) {
            memory.getCurrentStep().storeData(dataFactory.createData(PROPERTIES_EXTRACTED_IDENTIFIER, properties, true));
        }
    }