bug: wrong ion-segment-button class if no segement is checked initially

[NisStrom]

Bug Report

Ionic version:
[x] 5.x

Current behavior:
If an ion-segment initially has no checked segment button, once you select the first segment it does not set the segment-button-after-checked class to the following segment. This is due to the fact that in segment.tsx the checkButton method requires a previous element.

Expected behavior:
The ion-segment-button after the checked button should have the CSS class segment-button-after-checked.

Steps to reproduce:

1. Select second segment -> third segment should have class segment-button-after-checked

Related code:
https://stackblitz.com/edit/ionic-v4-angular-tabs-7kzv4u

[liamdebeasi]

Thanks for the issue. This has been resolved via #21547, and a fix will be available in an upcoming release of Ionic Framework.

[ionitron-bot]

Thanks for the issue! This issue is being locked to prevent comments that are not relevant to the original issue. If this is still an issue with the latest version of Ionic, please create a new issue and ensure the template is fully filled out.