Fixing fatal error found when upgrading WooCommerce plugin

[davefx]

What

Fixes woocommerce/woocommerce#43649

Why

Adds an extra check so, if $images hasn't been defined, the site doesn't generate a fatal error

Testing Instructions

Please consider any edge cases this change may have, and also other areas of the product this may impact.

• Do not include in the Testing Notes
• Should be tested by the development team exclusively

Screenshots or screencast

Before	After

WooCommerce Visibility

Required:

• WooCommerce Core
• Feature plugin
• Experimental
• N/A

Checklist

Required:

• This PR has either a [type] label or a [skip-changelog] label.
• This PR is assigned to a milestone.

Conditional:

• This PR has a UI change and has been cross-browser tested at different viewport sizes on both the frontend and in the editor.
• This PR has a changelog description (if [skip-changelog] label is not present).
• This PR adds/removes a feature flag & I've updated this doc.
• This PR adds/removes an experimental interfaces, and I've updated this doc.
• This PR has been accessibility tested.
• This PR has had any necessary documentation added/updated.

Changelog

Fixes a potential fatal error with certain themes and plugins if $images are not defined when rendering patterns.

[github-actions]

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WooCommerce Blocks has been merged into the WooCommerce Monorepo.

From now on, please open any issues or pull requests in the woocommerce/woocommerce repository.