Test case for https://github.com/WordPress/gutenberg/issues/10301

test-block.js

const {
	registerBlockType,
} = wp.blocks;

const {
	InnerBlocks,
} = wp.editor;

export default registerBlockType( 'test/should-not-accept-paragraph', {
	title: 'Test Block',
	category: 'common',
	attributes: {},

	edit: props => {

		return (
			<InnerBlocks
				allowedBlocks={ [ 'core/html' ] }
			/>
		)
	},

	save: function( props ) {
		return null;
	},
} );