Move attribute registration to function called in widget initialization

packages/customize-widgets/src/index.js

@@ -8,6 +8,7 @@ import {
 	__experimentalRegisterExperimentalCoreBlocks,
 } from '@wordpress/block-library';
 import {
+	registerInternalWidgetIds,
 	registerLegacyWidgetBlock,
 	registerLegacyWidgetVariations,
 	registerWidgetGroupBlock,
@@ -59,6 +60,8 @@ export function initialize( editorName, blockEditorSettings ) {
 			block.name.startsWith( 'core/navigation' )
 		);
 	} );
+
+	registerInternalWidgetIds();
 	registerCoreBlocks( coreBlocks );
 	registerLegacyWidgetBlock();
 	if ( process.env.IS_GUTENBERG_PLUGIN ) {

packages/edit-widgets/src/index.js

@@ -16,6 +16,7 @@ import {
 } from '@wordpress/block-library';
 import { __experimentalFetchLinkSuggestions as fetchLinkSuggestions } from '@wordpress/core-data';
 import {
+	registerInternalWidgetIds,
 	registerLegacyWidgetBlock,
 	registerLegacyWidgetVariations,
 	registerWidgetGroupBlock,
@@ -85,7 +86,10 @@ export function initialize( id, settings ) {
 		themeStyles: true,
 	} );
 
+	registerInternalWidgetIds();
+
 	dispatch( blocksStore ).__experimentalReapplyBlockTypeFilters();
+
 	registerCoreBlocks( coreBlocks );
 	registerLegacyWidgetBlock();
 	if ( process.env.IS_GUTENBERG_PLUGIN ) {

packages/widgets/src/utils.js

@@ -27,8 +27,13 @@ export function getWidgetIdFromBlock( block ) {
  * @return {Block} The updated block.
  */
 export function addWidgetIdToBlock( block, widgetId ) {
-	block.attributes.__internalWidgetId = widgetId;
-	return block;
+	return {
+		...block,
+		attributes: {
+			...( block.attributes || {} ),
+			__internalWidgetId: widgetId,
+		},
+	};
 }
 
 /**
@@ -39,7 +44,7 @@ export function addWidgetIdToBlock( block, widgetId ) {
  *
  * @return {Object} Updated block settings.
  */
-function addAttributes( settings ) {
+function addInternalWidgetIdAttribute( settings ) {
 	return {
 		...settings,
 		attributes: {
@@ -52,8 +57,10 @@ function addAttributes( settings ) {
 	};
 }
 
-addFilter(
-	'blocks.registerBlockType',
-	'core/widget/addAttributes',
-	addAttributes
-);
+export function registerInternalWidgetIds() {
+	addFilter(
+		'blocks.registerBlockType',
+		'core/widget/addAttributes',
+		addInternalWidgetIdAttribute
+	);
+}