Prevent Gutenberg Block from deletion

blockDeletionBlocker.js

const blockNameToPrevent = 'core/block';

const getBlockList = () => wp.data.select( 'core/block-editor' ).getBlocks();
let blockList = getBlockList();
	wp.data.subscribe( () => {
		const newBlockList = getBlockList();
		const blockListChanged = newBlockList !== blockList;

		if ( blockListChanged && newBlockList.length < blockList.length ) {
			const removedBlock = blockList.filter( ( x ) => ! newBlockList.includes( x ) )[ 0 ];
			if ( ! removedBlock || removedBlock.name !== blockNameToPrevent ) {
				return;
			}

			const removedBlockIndex = blockList.indexOf( removedBlock );

			warningBlock = wp.blocks.createBlock( 'core/block', { ref: removedBlock.attributes.ref } );

			wp.data.dispatch( 'core/block-editor' ).insertBlocks( warningBlock, removedBlockIndex );
			blockList = newBlockList;
		}
	} );

Since there is no possibility to undo the last action, the trick is to look at the list of blocks and add again the block that has just been deleted.

On paper, it is simple, and it should work, but for some reason the addition does not work and does not produce any errors…

blockDeletionBlocker.js