Fix updating state in unmounted components

packages/edit-site/src/components/add-new-template/new-template-part.js

@@ -26,7 +26,7 @@ export default function NewTemplatePart( { postType } ) {
 	const { saveEntityRecord } = useDispatch( coreStore );
 	const { getLastEntitySaveError } = useSelect( coreStore );
 
-	async function createTemplatePart( { title, area } ) {
+	async function createTemplatePart( { title, area }, { closeModal } ) {
 		if ( ! title ) {
 			createErrorNotice( __( 'Title is not defined.' ), {
 				type: 'snackbar',
@@ -55,6 +55,8 @@ export default function NewTemplatePart( { postType } ) {
 				throw lastEntitySaveError;
 			}
 
+			closeModal();
+
 			// Navigate to the created template part editor.
 			history.push( {
 				postId: templatePart.id,
@@ -71,6 +73,8 @@ export default function NewTemplatePart( { postType } ) {
 					  );
 
 			createErrorNotice( errorMessage, { type: 'snackbar' } );
+
+			closeModal();
 		}
 	}
 

packages/edit-site/src/components/create-template-part-modal/index.js

@@ -51,9 +51,7 @@ export default function CreateTemplatePartModal( { closeModal, onCreate } ) {
 						return;
 					}
 					setIsSubmitting( true );
-					await onCreate( { title, area } );
-					setIsSubmitting( false );
-					closeModal();
+					await onCreate( { title, area }, { closeModal } );
 				} }
 			>
 				<TextControl

packages/edit-site/src/components/edit-template-part-menu-button/index.js

@@ -54,8 +54,8 @@ function EditTemplatePartMenuItem( { selectedClientId, onClose } ) {
 
 	const linkProps = useLink(
 		{
-			postId: selectedTemplatePart.id,
-			postType: selectedTemplatePart.type,
+			postId: selectedTemplatePart?.id,
+			postType: selectedTemplatePart?.type,
 		},
 		{
 			fromTemplateId: params.postId,

packages/edit-site/src/components/template-part-converter/convert-to-template-part.js

@@ -50,16 +50,18 @@ export default function ConvertToTemplatePart( { clientIds, blocks } ) {
 		createSuccessNotice( __( 'Template part created.' ), {
 			type: 'snackbar',
 		} );
+
+		// The modal and this component will be unmounted because of `replaceBlocks` above,
+		// so no need to call `closeModal` or `onClose`.
 	};
 
 	return (
 		<>
 			<BlockSettingsMenuControls>
-				{ ( { onClose } ) => (
+				{ () => (
 					<MenuItem
 						onClick={ () => {
 							setIsModalOpen( true );
-							onClose();
 						} }
 					>
 						{ __( 'Make template part' ) }