Fix 读取空行NPE错误

hutool-poi/src/main/java/cn/hutool/poi/excel/cell/CellUtil.java

@@ -203,6 +203,9 @@ public class CellUtil {
 	 * @since 5.5.0
 	 */
 	public static Cell getCell(Row row, int cellIndex) {
+		if (null == row) {
+			return null;
+		}
 		Cell cell = row.getCell(cellIndex);
 		if (null == cell) {
 			return new NullCell(row, cellIndex);
@@ -219,6 +222,9 @@ public class CellUtil {
 	 * @since 4.0.2
 	 */
 	public static Cell getOrCreateCell(Row row, int cellIndex) {
+		if (null == row) {
+			return null;
+		}
 		Cell cell = row.getCell(cellIndex);
 		if (null == cell) {
 			cell = row.createCell(cellIndex);

hutool-poi/src/test/java/cn/hutool/poi/excel/ExcelReadTest.java

@@ -244,4 +244,10 @@ public class ExcelReadTest {
 		Assert.assertEquals("李四", objects.get(1));
 		Assert.assertEquals("", objects.get(2));
 	}
+
+	@Test
+	public void readColumnNPETest() {
+		ExcelReader reader = ExcelUtil.getReader(ResourceUtil.getStream("read_row_npe.xlsx"));
+		reader.readColumn(0, 1);
+	}
 }