Fixes #2411
Additional context:

• Slack: p1723238434529699-slack-C055WHLA98D
• Forums: https://wordpress.org/support/topic/connecting-to-stripe-causes-critical-error/

Changes proposed in this Pull Request:

This PR fixes a fatal error issue that is happening to some merchants. When trying to merge the existing Stripe settings with the updated version, some merchants are getting an error like:

Uncaught TypeError: array_merge(): Argument #2 must be of type array, string given in /wp-content/plugins/woocommerce-gateway-stripe/includes/connect/class-wc-stripe-connect.php:153

or

Uncaught TypeError: array_merge(): Argument #2 must be of type array, bool given in /wp-content/plugins/woocommerce-gateway-stripe/includes/connect/class-wc-stripe-connect.php:153

This means that get_option on includes/connect/class-wc-stripe-connect.php#153 returns an invalid value.

I could not reproduce this issue using PHP 8.1, 8.2, or 8.3 as merchants reported. So, for extra safety, the fix consists of checking if the returning value is a valid array.

Testing instructions

A code review should be enough since no way to reproduce this issue correctly has been found yet. Check if the change looks safe enough for you.

You can also make some tests by hardcoding the value of $current_options (includes/connect/class-wc-stripe-connect.php#153) to different types and connect your Stripe account.

• Covered with tests (or have a good reason not to test in description ☝️)
• Added changelog entry in both changelog.txt and readme.txt (or does not apply)
• Tested on mobile (or does not apply)

Post merge

• Added testing instructions to the Release Testing Instructions wiki page (or does not apply)
• Added the needs docs label (or does not apply)
• Included this PR in the Release Thread scope (or does not apply)

cc @diegocurbelo @c-shultz