fix: handle undefined selectedAccount in updateAccounts

[montelaidev]

Explanation

This PR fixes updateAccounts in the AccountsController to handle the edge case where the selected account is undefined. This follows the same logic used in onKeyringStateChange

References

Fixes: MetaMask/metamask-extension#26377

Changelog

@metamask/accounts-controller

• FIXED: updateAccounts logic to handle when the selectedAccount is undefined.

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've highlighted breaking changes using the "BREAKING" category above as appropriate