fix: fix nil sheet model append nil pointer reference.

Author: VarusHsu

build.go

@@ -84,6 +84,9 @@ func write(sheetModels []SheetModel, opts ...Option) (*excelize.File, error) {
 	f := excelize.NewFile()
 	sheetLinesCount := make(map[string]int)
 	for _, sheetModel := range sheetModels {
+		if sheetModel == nil {
+			return nil, errors.New("nil reference row append is not allowed")
+		}
 		sheetName := sheetModel.SheetName()
 		if sheetName == "" {
 			return nil, errors.New("sheetModel must have a sheet name")

build_test.go

@@ -379,3 +379,11 @@ func TestWithHeadless(t *testing.T) {
 		t.Error(err)
 	}
 }
+
+func TestAppendNilRow(t *testing.T) {
+	var models []SheetModel
+	models = append(models, nil)
+	err := WriteExcelSaveAs("test16.xlsx", models)
+	assert.EqualError(t, err, "nil reference row append is not allowed")
+
+}