fix: wire ErrorBoundary attachment builder for React Native

@bugsplat/react@2.1 moved the componentStack attachment shape behind a
Scope-injected builder; the default produces a browser Blob, which RN's
FormData polyfill can't serialize. @bugsplat/expo installs an RN-safe
builder (base64 data URI inside the { uri, type } file-ref shape RN
streams as a real multipart file part) on appScope at the top of init(),
synchronously before any awaits so an ErrorBoundary catching during
startup doesn't race the default.

Also updates the jest mocks in the native and Expo Go suites to expose
the appScope.setCreateComponentStackAttachment setter, plus a new test
that round-trips the installed builder through init() to verify the
shape.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: bobbyg603

package-lock.json

@@ -1,4 +1,5 @@
-import { type BugSplat, init as initReact } from '@bugsplat/react';
+import { appScope, type BugSplat, init as initReact } from '@bugsplat/react';
+import type { BugSplatAttachment } from 'bugsplat';
 
 import type {
   BugSplatFeedbackOptions,
@@ -14,6 +15,36 @@ export const nativeAvailable = BugsplatExpoModule != null;
 let jsClient: BugSplat | null = null;
 const jsAttributes: Record<string, string> = {};
 
+function utf8ToBase64(text: string): string {
+  const NodeBuffer = (
+    globalThis as {
+      Buffer?: { from(s: string, enc: string): { toString(enc: string): string } };
+    }
+  ).Buffer;
+  if (NodeBuffer) {
+    return NodeBuffer.from(text, 'utf-8').toString('base64');
+  }
+  return btoa(unescape(encodeURIComponent(text)));
+}
+
+/**
+ * React Native-compatible componentStack attachment builder. RN's FormData
+ * polyfill can't serialize browser `Blob`s, so we hand it a `data:` URI inside
+ * the `{ uri, type }` file-ref shape that RN's fetch uploads as a real file
+ * part.
+ */
+function rnCreateComponentStackAttachment(
+  componentStack: string
+): BugSplatAttachment {
+  return {
+    filename: 'componentStack.txt',
+    data: {
+      uri: `data:text/plain;base64,${utf8ToBase64(componentStack)}`,
+      type: 'text/plain',
+    },
+  };
+}
+
 function applyDefaults(client: BugSplat, options?: BugSplatInitOptions): void {
   if (options?.appKey) client.setDefaultAppKey(options.appKey);
   if (options?.userName) client.setDefaultUser(options.userName);
@@ -42,6 +73,11 @@ export async function init(
   version: string,
   options?: BugSplatInitOptions
 ): Promise<void> {
+  // Tell bugsplat-react's ErrorBoundary how to build its componentStack
+  // attachment on React Native. Set synchronously before any awaits so an
+  // ErrorBoundary that catches during startup doesn't race the default.
+  appScope.setCreateComponentStackAttachment(rnCreateComponentStackAttachment);
+
   if (nativeAvailable) {
     await BugsplatExpoModule!.init(database, application, version, options as Record<string, unknown>);
     initReact({ database, application, version })((client) => {

src/BugsplatExpo.ts

@@ -22,8 +22,13 @@ const mockInitReact = jest.fn().mockReturnValue(
   }
 );
 
+const mockSetCreateComponentStackAttachment = jest.fn();
+
 jest.mock('@bugsplat/react', () => ({
   init: mockInitReact,
+  appScope: {
+    setCreateComponentStackAttachment: mockSetCreateComponentStackAttachment,
+  },
 }));
 
 import {

src/__tests__/BugsplatExpo.expoGo.test.ts

@@ -31,8 +31,13 @@ const mockInitReact = jest.fn().mockReturnValue(
   }
 );
 
+const mockSetCreateComponentStackAttachment = jest.fn();
+
 jest.mock('@bugsplat/react', () => ({
   init: mockInitReact,
+  appScope: {
+    setCreateComponentStackAttachment: mockSetCreateComponentStackAttachment,
+  },
 }));
 
 import {
@@ -70,6 +75,20 @@ describe('BugsplatExpo (native)', () => {
       });
     });
 
+    it('installs an RN-compatible componentStack attachment builder on appScope', async () => {
+      await init('test-db', 'MyApp', '1.0.0');
+      expect(mockSetCreateComponentStackAttachment).toHaveBeenCalledTimes(1);
+      const [builder] = mockSetCreateComponentStackAttachment.mock.calls[0];
+      const attachment = builder('at BuggyComponent\n  at ErrorBoundary');
+      expect(attachment).toEqual({
+        filename: 'componentStack.txt',
+        data: {
+          uri: expect.stringMatching(/^data:text\/plain;base64,/),
+          type: 'text/plain',
+        },
+      });
+    });
+
     it('passes options to native init', async () => {
       const options = {
         appKey: 'key123',