#fixed code
                                @Test
    public void testGetHalfMessageNull() {
        when(messageStore
                .getMessage(anyString(), anyString(), anyInt(), anyLong(), anyInt(), ArgumentMatchers.nullable(MessageFilter.class)))
                .thenReturn(null);
        PullResult result = transactionBridge.getHalfMessage(0, 0, 1);
        assertThat(result).isNull();
    }
#vulnerable code 
                                @Test
    public void testGetHalfMessageNull() {
        when(messageStore
                .getMessage(anyString(), anyString(), anyInt(), anyLong(), anyInt(), ArgumentMatchers.nullable(MessageFilter.class)))
                .thenReturn(null);
        PullResult result = transactionBridge.getHalfMessage(0, 0, 1);
        assertThat(result.getPullStatus()).isNull();
    } 
                            #location 7 
                            #vulnerability type NULL_DEREFERENCE