[rnmobile] Fix crash which occurs after deleting Image/Page break block

[marecar3]

Fixes: wordpress-mobile/WordPress-Android#10491

How has this been tested?

Steps to repro - Case A

• Create a new post
• Click on the empty paragraph block
• Add a Page break block
• Click on the "bin" on the Page break block
• Boom

Steps to repro - Case B

• Create a new post
• Add a Page break block
• Click on the "bin" on the Page break block
• This time the block is removed without a crash
• Add a Page break block
• Click on the "bin" on the Page break block
• Boom

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR. .

[SergioEstevao]

Working fine.

[marecar3]

Closing in favor of #18539