Description

When a raw transform returns an array of blocks instead of a single block, the result doesn't get handled correctly.

Step-by-step reproduction instructions

1. In the registerBlockType() call of a test block (using npx @wordpress/create-block test-block or something), add a transform like so:

   transforms: {
   	from: [
   		{
   			type: 'raw',
   			isMatch: () => true,
   			transform: () => {
   				const blocks = [
   					createBlock( 'create-block/test-block' ),
   					createBlock( 'create-block/test-block' ),
   				];
   
   				return blocks; /* doesn't work */
   				// return blocks[ 0 ]; /* this works */
   			},
   		},
   	],
   },

2. Go to the editor at /wp-admin/post-new.php and paste a string like <p>test block</p>.

Expected behaviour

The pasted string is transformed into two 'create-block/test-block' blocks.

Actual behaviour

Nothing happens (the pasted string just disappears without any error messages).

WordPress information

• WordPress version: 5.7-alpha-49991
• Gutenberg version: Current master (9.8.0 ?)
• Are all plugins except Gutenberg deactivated? Yes
• Are you using a default theme (e.g. Twenty Twenty-One)? Yes

Device information

• Device: Desktop
• Operating system: macOS 10.15.7
• Browser: Chrome 87.0.4280.141