The native editor crashes when a column block contains an empty width attribute.

Description

Step-by-step reproduction instructions

1. Open the native block editor (React Native editor)
2. Replace the editor contents with the following HTML and observe that the app crashes

<!-- wp:columns -->
	<div class="wp-block-columns">
		<!-- wp:column -->
			<div class="wp-block-column"></div>
		<!-- /wp:column -->

		<!-- wp:column {"width":""} -->
			<div class="wp-block-column"></div>
		<!-- /wp:column -->
	</div>
<!-- /wp:columns -->

Expected behaviour

The native editor should ignore the empty width attribute just as the web editor does

Actual behaviour

The native editor crashes when it encounters an empty width attribute in a column block.

WordPress information

Current master branch: 6ef9e82

Device information

iOS or Android