Created attachment 33760 [details]
The sample file to reproduce the issue

If you try to process the table with a table cell having the null descriptor, we get the Null pointer exception. The sample file to reproduce the issue is also attached.

CODE :

import org.apache.poi.hwpf.HWPFDocument;
import org.apache.poi.hwpf.HWPFDocumentCore;
import org.apache.poi.hwpf.converter.WordToHtmlConverter;
import org.w3c.dom.Document;

import javax.xml.parsers.DocumentBuilderFactory;
import java.io.File;
import java.io.FileInputStream;

public class PoiIssues {

    public static void main(String[] args) throws Exception {
        File file = new File("word-doc-with-revised-table.doc");
        FileInputStream fileInputStream = new FileInputStream(file);
        Document document = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
        WordToHtmlConverter wordToHtmlConverter = new WordToHtmlConverter(document);
        HWPFDocumentCore hwpfDocumentCore = new HWPFDocument(HWPFDocumentCore.verifyAndBuildPOIFS(fileInputStream));
        wordToHtmlConverter.processDocument(hwpfDocumentCore);
        System.out.println(document.toString());
        System.out.println("Process Complete");
    }
}


EXCEPTION :

Exception in thread "main" java.lang.NullPointerException
	at org.apache.poi.hwpf.usermodel.TableCell.isVerticallyMerged(TableCell.java:66)
	at org.apache.poi.hwpf.converter.WordToHtmlConverter.processTable(WordToHtmlConverter.java:643)
	at org.apache.poi.hwpf.converter.AbstractWordConverter.processParagraphes(AbstractWordConverter.java:1073)
	at org.apache.poi.hwpf.converter.WordToHtmlConverter.processSingleSection(WordToHtmlConverter.java:608)
	at org.apache.poi.hwpf.converter.AbstractWordConverter.processDocument(AbstractWordConverter.java:721)
	at PoiIssues.main(PoiIssues.java:20)