fix bug

src/main/java/com/gmh/controller/ExcelController.java

@@ -40,6 +40,9 @@ public class ExcelController {
                 int lastCellNum = row.getLastCellNum();
                 for (int c = 0; c < lastCellNum; c++) {
                     Cell cell = row.getCell(c);
+                    if (cell == null) {
+                        continue;
+                    }
                     String stringCellValue = POIExcelUtil.getStringCellValExcludeBlank(cell);
                     if (r == 0) {
                         // 第一行有姓名列