handle expires_in when encoded as string
diff --git a/lib/src/handle_access_token_response.dart b/lib/src/handle_access_token_response.dart
index 83d57fa..4c92810 100644
--- a/lib/src/handle_access_token_response.dart
+++ b/lib/src/handle_access_token_response.dart
@@ -71,14 +71,14 @@
     if (expiresIn != null) {
       if (expiresIn is String) {
         try {
-          expiresIn = double.tryParse(expiresIn)!.toInt();
-        } catch (e) {
+          expiresIn = double.parse(expiresIn).toInt();
+        } on FormatException {
           throw FormatException(
-              'parameter "expires_in" was not an int, and given string cant not be parsed to int : "$expiresIn"');
+              'parameter "expires_in" could not be parsed as in, was: "$expiresIn"');
         }
       } else if (expiresIn is! int) {
         throw FormatException(
-            'parameter "expires_in" was not an int, was of type ${expiresIn.runtimeType.toString()} value : "$expiresIn"');
+            'parameter "expires_in" was not an int, was: "$expiresIn"');
       }
     }