Core: Add Story Index error handling

lib/api/src/lib/StoryIndexClient.ts

@@ -21,6 +21,8 @@ export class StoryIndexClient extends EventSource {
 
   async fetch() {
     const result = await fetch(PATH);
-    return result.json() as StoryIndex;
+    if (result.status === 200) return result.json() as StoryIndex;
+
+    throw new Error(await result.text());
   }
 }

lib/api/src/modules/stories.ts

@@ -354,15 +354,22 @@ export const init: ModuleFn = ({
       });
     },
     fetchStoryList: async () => {
-      const storyIndex = await indexClient.fetch();
+      try {
+        const storyIndex = await indexClient.fetch();
 
-      // We can only do this if the stories.json is a proper storyIndex
-      if (storyIndex.v !== 3) {
-        logger.warn(`Skipping story index with version v${storyIndex.v}, awaiting SET_STORIES.`);
-        return;
-      }
+        // We can only do this if the stories.json is a proper storyIndex
+        if (storyIndex.v !== 3) {
+          logger.warn(`Skipping story index with version v${storyIndex.v}, awaiting SET_STORIES.`);
+          return;
+        }
 
-      await fullAPI.setStoryList(storyIndex);
+        await fullAPI.setStoryList(storyIndex);
+      } catch (err) {
+        store.setState({
+          storiesConfigured: true,
+          storiesFailed: err,
+        });
+      }
     },
     setStoryList: async (storyIndex: StoryIndex) => {
       const hash = transformStoryIndexToStoriesHash(storyIndex, {

lib/preview-web/src/PreviewWeb.integration.test.ts

@@ -38,7 +38,7 @@ jest.mock('global', () => ({
   FEATURES: {
     storyStoreV7: true,
   },
-  fetch: async () => ({ json: async () => mockStoryIndex }),
+  fetch: async () => ({ status: 200, json: async () => mockStoryIndex, text: () => 'error text' }),
 }));
 
 beforeEach(() => {

lib/preview-web/src/PreviewWeb.test.ts

@@ -25,6 +25,7 @@ const { history, document } = global;
 
 const mockStoryIndex = jest.fn(() => storyIndex);
 
+let mockFetchResult;
 jest.mock('global', () => ({
   ...(jest.requireActual('global') as any),
   history: { replaceState: jest.fn() },
@@ -39,7 +40,7 @@ jest.mock('global', () => ({
     breakingChangesV7: true,
     // xxx
   },
-  fetch: async () => ({ json: mockStoryIndex }),
+  fetch: async () => mockFetchResult,
 }));
 
 jest.mock('@storybook/client-logger');
@@ -70,10 +71,11 @@ beforeEach(() => {
   mockStoryIndex.mockReset().mockReturnValue(storyIndex);
 
   addons.setChannel(mockChannel as any);
+  mockFetchResult = { status: 200, json: mockStoryIndex, text: () => 'error text' };
 });
 
 describe('PreviewWeb', () => {
-  describe('constructor', () => {
+  describe('initialize', () => {
     it('shows an error if getProjectAnnotations throws', async () => {
       const err = new Error('meta error');
       const preview = new PreviewWeb();
@@ -87,9 +89,18 @@ describe('PreviewWeb', () => {
       expect(preview.view.showErrorDisplay).toHaveBeenCalled();
       expect(mockChannel.emit).toHaveBeenCalledWith(Events.CONFIG_ERROR, err);
     });
-  });
 
-  describe('initialize', () => {
+    it('shows an error if the stories.json endpoint 500s', async () => {
+      const err = new Error('sort error');
+      mockFetchResult = { status: 500, text: async () => err.toString() };
+
+      const preview = new PreviewWeb();
+      await preview.initialize({ importFn, getProjectAnnotations });
+
+      expect(preview.view.showErrorDisplay).toHaveBeenCalled();
+      expect(mockChannel.emit).toHaveBeenCalledWith(Events.CONFIG_ERROR, expect.any(Error));
+    });
+
     it('sets globals from the URL', async () => {
       document.location.search = '?id=*&globals=a:c';
 

lib/preview-web/src/PreviewWeb.tsx

@@ -97,15 +97,21 @@ export class PreviewWeb<TFramework extends AnyFramework> {
 
     if (FEATURES?.storyStoreV7) {
       this.indexClient = new StoryIndexClient();
-      return this.indexClient.fetch().then((fetchedStoryIndex: StoryIndex) => {
-        this.storyStore.initialize({
-          getStoryIndex: () => fetchedStoryIndex,
-          importFn,
-          projectAnnotations,
-          cache: false,
+      return this.indexClient
+        .fetch()
+        .then((fetchedStoryIndex: StoryIndex) => {
+          this.storyStore.initialize({
+            getStoryIndex: () => fetchedStoryIndex,
+            importFn,
+            projectAnnotations,
+            cache: false,
+          });
+          return this.setupListenersAndRenderSelection();
+        })
+        .catch((err) => {
+          logger.warn(err);
+          this.renderPreviewEntryError(err);
         });
-        return this.setupListenersAndRenderSelection();
-      });
     }
 
     if (!getStoryIndex) {

lib/preview-web/src/StoryIndexClient.ts

@@ -20,6 +20,9 @@ export class StoryIndexClient extends EventSource {
 
   async fetch() {
     const result = await fetch(PATH);
-    return result.json() as StoryIndex;
+
+    if (result.status === 200) return result.json() as StoryIndex;
+
+    throw new Error(await result.text());
   }
 }