Apply Gemini error formatting suggestions in app-facing package

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: stuartmorgan-g

packages/local_auth/local_auth/example/lib/main.dart

@@ -97,7 +97,7 @@ class _MyAppState extends State<MyApp> {
         _isAuthenticating = false;
         if (e.code != LocalAuthExceptionCode.userCanceled &&
             e.code != LocalAuthExceptionCode.systemCanceled) {
-          _authorized = 'Error - ${e.code.name}: ${e.description}';
+          _authorized = 'Error - ${e.code.name}${e.description != null ? ': ${e.description}' : ''}';
         }
       });
       return;
@@ -141,7 +141,7 @@ class _MyAppState extends State<MyApp> {
         _isAuthenticating = false;
         if (e.code != LocalAuthExceptionCode.userCanceled &&
             e.code != LocalAuthExceptionCode.systemCanceled) {
-          _authorized = 'Error - ${e.code.name}: ${e.description}';
+          _authorized = 'Error - ${e.code.name}${e.description != null ? ': ${e.description}' : ''}';
         }
       });
       return;