Update handle_access_token_response.dart
diff --git a/lib/src/handle_access_token_response.dart b/lib/src/handle_access_token_response.dart
index ba78d94..83d57fa 100644
--- a/lib/src/handle_access_token_response.dart
+++ b/lib/src/handle_access_token_response.dart
@@ -71,7 +71,7 @@
if (expiresIn != null) {
if (expiresIn is String) {
try {
- expiresIn = double.tryParse(expiresIn).toInt();
+ expiresIn = double.tryParse(expiresIn)!.toInt();
} catch (e) {
throw FormatException(
'parameter "expires_in" was not an int, and given string cant not be parsed to int : "$expiresIn"');