add migration task

Author: Rich-Harris

packages/migrate/migrations/app-state/migrate.js

@@ -38,6 +38,8 @@ export function transform_svelte_code(code) {
 	});
 	let modified = code.replace('$app/stores', '$app/state');
 
+	let needs_navigating_migration_task = false;
+
 	for (const [store, alias] of stores) {
 		// if someone uses that they're deep into stores and we better not touch this file
 		if (store === 'getStores') return code;
@@ -68,10 +70,18 @@ export function transform_svelte_code(code) {
 				return code;
 			}
 
+			if (store === 'navigating' && after[0] !== '.') {
+				needs_navigating_migration_task = true;
+			}
+
 			modified = before.slice(0, -1) + alias + (store === 'updated' ? '.current' : '') + after;
 			count_removed++;
 		}
 	}
 
+	if (needs_navigating_migration_task) {
+		modified = `<!-- @migration task: review uses of \`navigating\` -->\n${modified}`;
+	}
+
 	return modified;
 }

packages/migrate/migrations/app-state/migrate.spec.js

@@ -40,7 +40,7 @@ test('Updates $app/store #2', () => {
 	);
 	assert.equal(
 		result,
-		`<script>
+		`<!-- @migration task: review uses of \`navigating\` -->\n<script>
 	import { navigating, updated } from '$app/state';
 	updated.current;
 	updated.check();