fix(crash): stop reporting transient google_fonts failures as fatal

google_fonts downloads fonts over HTTP on first use. When the device is
offline or the font CDN fails, the load throws an uncaught async error
that PlatformDispatcher.onError recorded to Crashlytics with
fatal: true. The app keeps running with a fallback font, so this is a
transient, non-fatal condition — reporting it as fatal distorts the
crash-free metric.

Classify google_fonts font-fetch failures (by exception message and by
google_fonts stack frames) and record them as non-fatal in both the
Flutter and async error handlers.

https://claude.ai/code/session_0135nVBYGpwkaQvG13XyS66H

Author: claude

lib/main.dart

@@ -30,12 +30,24 @@ void main() async {
       options: DefaultFirebaseOptions.currentPlatform,
     );
 
-    // Pass all uncaught Flutter errors to Crashlytics
-    FlutterError.onError = FirebaseCrashlytics.instance.recordFlutterFatalError;
+    // Pass all uncaught Flutter errors to Crashlytics. Transient google_fonts
+    // font-fetch failures are downgraded to non-fatal (see
+    // isTransientFontLoadError).
+    FlutterError.onError = (details) {
+      if (isTransientFontLoadError(details.exception, details.stack)) {
+        FirebaseCrashlytics.instance.recordFlutterError(details);
+      } else {
+        FirebaseCrashlytics.instance.recordFlutterFatalError(details);
+      }
+    };
 
     // Pass all uncaught asynchronous errors to Crashlytics
     PlatformDispatcher.instance.onError = (error, stack) {
-      FirebaseCrashlytics.instance.recordError(error, stack, fatal: true);
+      FirebaseCrashlytics.instance.recordError(
+        error,
+        stack,
+        fatal: !isTransientFontLoadError(error, stack),
+      );
       return true;
     };
 
@@ -49,6 +61,18 @@ void main() async {
   runApp(const BeerFestivalApp());
 }
 
+/// Whether [error] originates from `google_fonts` runtime font fetching.
+///
+/// google_fonts downloads fonts over HTTP on first use. When the device is
+/// offline or the font CDN fails, the load throws an uncaught async error.
+/// The app keeps running with a fallback font, so such failures are transient
+/// and non-fatal — they must not be recorded to Crashlytics as fatal crashes,
+/// which would otherwise distort the crash-free metric.
+bool isTransientFontLoadError(Object error, StackTrace? stack) {
+  if (error.toString().contains('Failed to load font')) return true;
+  return stack != null && stack.toString().contains('google_fonts');
+}
+
 
 class BeerFestivalApp extends StatelessWidget {
   const BeerFestivalApp({super.key});

test/main_test.dart

@@ -397,4 +397,37 @@ void main() {
       expect(find.text('Drink Detail'), findsOneWidget);
     });
   });
+
+  group('isTransientFontLoadError', () {
+    test('detects google_fonts HTTP fetch failure by message', () {
+      final error = Exception(
+        'Failed to load font with url: https://fonts.gstatic.com/s/a/abc.ttf',
+      );
+      expect(isTransientFontLoadError(error, StackTrace.empty), isTrue);
+    });
+
+    test('detects font load failure by google_fonts stack frames', () {
+      // A network-level exception whose message gives no hint, but whose
+      // stack trace runs through the google_fonts package.
+      final stack = StackTrace.fromString(
+        '#0  _httpFetchFontAndSaveToDevice (package:google_fonts/src/google_fonts_base.dart:288)\n'
+        '#1  loadFontIfNecessary (package:google_fonts/src/google_fonts_base.dart:175)',
+      );
+      expect(
+        isTransientFontLoadError(Exception('connection refused'), stack),
+        isTrue,
+      );
+    });
+
+    test('does not flag unrelated application errors as font errors', () {
+      final stack = StackTrace.fromString(
+        '#0  BeerProvider.loadDrinks (package:cambridge_beer_festival/providers/beer_provider.dart:270)',
+      );
+      expect(
+        isTransientFontLoadError(Exception('Something went wrong'), stack),
+        isFalse,
+      );
+      expect(isTransientFontLoadError(StateError('bad state'), null), isFalse);
+    });
+  });
 }