This closes #714 and closes #715, fix wrong worksheet index returned by NewSheet in some case, fix panic on formatted value with no built-in number format ID

1 files changed, 3 insertions, 2 deletions

diff --git a/sheet.go b/sheet.go
index aaa72cc..44067fe 100644
--- a/sheet.go
+++ b/sheet.go
@@ -37,8 +37,9 @@ import (
 // appending the new sheet.
 func (f *File) NewSheet(name string) int {
 	// Check if the worksheet already exists
-	if f.GetSheetIndex(name) != -1 {
-		return f.SheetCount
+	index := f.GetSheetIndex(name)
+	if index != -1 {
+		return index
 	}
 	f.DeleteSheet(name)
 	f.SheetCount++