Keep a Data Library entry whose layer fails to tear down

Remove dropped an entry from the selection and reported success even
when the manager could not disable or destroy its layer, leaving a
registered, possibly visible layer that Browse, share links and saved
state no longer knew. Remove now keeps the entry and reports failure,
so its row and Remove all still reach it and a later Remove can retry.

src/library/controller.js

@@ -325,8 +325,13 @@ export function createDataLibrary({
   async function remove(id) {
     if (destroyed || pending.has(id)) return false;
     const work = (async () => {
-      if (isRegistered(id))
-        await dataManager.unregisterLibraryLayer(libraryLayerId(id));
+      // A layer that would not tear down is still there: keep it in the
+      // library so its row, Remove and Remove all still reach it.
+      if (
+        isRegistered(id) &&
+        !(await dataManager.unregisterLibraryLayer(libraryLayerId(id)))
+      )
+        return false;
       selection = {
         added: selection.added.filter((other) => other !== id),
         on: selection.on.filter((other) => other !== id),

src/library/controller.test.mjs

@@ -403,6 +403,47 @@ test('a full library refuses another entry before its layer exists', async (t) =
   opened.destroy();
 });
 
+test('a layer that fails to tear down stays in the library', async (t) => {
+  const manager = sealedManager(t);
+  const storage = memoryStorage();
+  const library = createDataLibrary({
+    entries,
+    ledger,
+    dataManager: manager,
+    services: {},
+    storage,
+    shareLink: fakeShareLink(null),
+    source: source({}),
+  });
+  await library.start();
+  await library.add('night-lights');
+  const { module } = manager.layers.get('lib-night-lights');
+  const disable = module.disable;
+  module.disable = async () => {
+    throw new Error('stuck');
+  };
+  t.mock.method(console, 'warn', () => {});
+  try {
+    assert.equal(await library.remove('night-lights'), false);
+    assert.equal(await library.reset(), 0);
+    assert.equal(manager.layers.has('lib-night-lights'), true);
+    assert.deepEqual(
+      JSON.parse(storage.store.get(LIBRARY_STORAGE_KEY)).added,
+      ['night-lights'],
+    );
+    assert.equal(
+      library.list().find((row) => row.entry.id === 'night-lights').added,
+      true,
+    );
+  } finally {
+    // Once it tears down, Remove works (and the manager can shut down).
+    module.disable = disable;
+  }
+  assert.equal(await library.remove('night-lights'), true);
+  assert.equal(manager.layers.has('lib-night-lights'), false);
+  library.destroy();
+});
+
 test('zoom flies to an added layer through the caller, reset removes everything', async (t) => {
   const manager = sealedManager(t);
   const storage = memoryStorage();