Fix worker in subfolder not found

packages/wmr/src/plugins/worker-plugin.js

@@ -118,8 +118,9 @@ export function workerPlugin(options) {
 						}
 
 						const start = match.index + match[0].indexOf(spec);
-						// Account for quoting characters
-						s.overwrite(start - 1, start + spec.length + 1, `import.meta.ROLLUP_FILE_URL_${ref}`);
+						// Account for quoting characters and force URL to be
+						// relative.
+						s.overwrite(start - 1, start + spec.length + 1, `'.' + import.meta.ROLLUP_FILE_URL_${ref}`);
 					}
 
 					return {

packages/wmr/test/fixtures/worker-relative/foo/foo.worker.js

@@ -0,0 +1,3 @@
+addEventListener('message', () => {
+	postMessage('it works');
+});

packages/wmr/test/fixtures/worker-relative/foo/index.js

@@ -0,0 +1,7 @@
+const worker = new Worker(new URL('./foo.worker.js', import.meta.url));
+
+worker.addEventListener('message', e => {
+	document.querySelector('h1').textContent = e.data;
+});
+
+worker.postMessage('hello');

packages/wmr/test/fixtures/worker-relative/index.html

@@ -0,0 +1,2 @@
+<h1>it doesn't work</h1>
+<script src="./index.js" type="module"></script>

packages/wmr/test/fixtures/worker-relative/index.js

@@ -0,0 +1 @@
+import './foo/index.js';