fix index out of range bug.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

plugin.go

@@ -141,7 +141,7 @@ func parseTo(to []string, authorEmail string, matchEmail bool) []int64 {
 	var ids []int64
 	attachEmail := true
 
-	for _, value := range to {
+	for _, value := range trimElement(to) {
 		idArray := trimElement(strings.Split(value, ":"))
 
 		// check id

plugin_test.go

@@ -146,6 +146,10 @@ func TestParseTo(t *testing.T) {
 
 	ids = parseTo(input, "a@gmail.com", true)
 	assert.Equal(t, []int64{0, 4, 5}, ids)
+
+	// test empty ids
+	ids = parseTo([]string{"", " ", "   "}, "a@gmail.com", true)
+	assert.Equal(t, 0, len(ids))
 }
 
 func TestCheckFileExist(t *testing.T) {