diff --git a/packages/api_client/lib/src/resources/questions_resource.dart b/packages/api_client/lib/src/resources/questions_resource.dart
index 3166f4b..55aee64 100644
--- a/packages/api_client/lib/src/resources/questions_resource.dart
+++ b/packages/api_client/lib/src/resources/questions_resource.dart
@@ -1,7 +1,7 @@
 import 'dart:convert';
-import 'dart:io';
 
 import 'package:api_client/api_client.dart';
+import 'package:cross_file/cross_file.dart';
 
 /// {@template questions_resource}
 /// An api resource to get response to question from the VERTEX api
@@ -21,22 +21,39 @@ class QuestionsResource {
   ///
   /// Returns a [List<String>].
   Future<VertexResponse> getVertexResponse(String query) async {
+    String body;
     if (_realApiEnabled) {
       final response = await _apiClient.get(
-        // TODO(oscar): update with real API once is enabled.
+        // TODO(oscar): update with real API once is enabled
+        // and add possible failures.
         'google.es',
         queryParameters: {
           'query': query,
         },
       );
-      final json = jsonDecode(response.body);
-      return VertexResponse.fromJson(json as Map<String, dynamic>);
+      if (response.statusCode != 200) {
+        throw ApiClientError(
+          'GET getVertexResponse with query=$query '
+          'returned status ${response.statusCode} '
+          'with the following response: "${response.body}"',
+          StackTrace.current,
+        );
+      }
+      body = response.body;
     } else {
       const path = 'lib/src/resources/fake_response.json';
-      final fakeResponse = await File(path).readAsString();
+      body = await XFile(path).readAsString();
+    }
 
-      final json = jsonDecode(fakeResponse) as Map<String, dynamic>;
+    try {
+      final json = jsonDecode(body) as Map<String, dynamic>;
       return VertexResponse.fromJson(json);
+    } catch (e) {
+      throw ApiClientError(
+        'GET getVertexResponse with query=$query '
+        'returned invalid response "$body"',
+        StackTrace.current,
+      );
     }
   }
 }
diff --git a/packages/api_client/pubspec.yaml b/packages/api_client/pubspec.yaml
index c9d52aa..abf074c 100644
--- a/packages/api_client/pubspec.yaml
+++ b/packages/api_client/pubspec.yaml
@@ -7,6 +7,7 @@ environment:
   sdk: ">=3.1.0 <4.0.0"
 
 dependencies:
+  cross_file: ^0.3.3+6
   equatable: ^2.0.5
   http: ^1.1.0
   json_annotation: ^4.8.1
diff --git a/packages/api_client/test/src/resources/questions_resource_test.dart b/packages/api_client/test/src/resources/questions_resource_test.dart
index 79165ce..6ff5fa9 100644
--- a/packages/api_client/test/src/resources/questions_resource_test.dart
+++ b/packages/api_client/test/src/resources/questions_resource_test.dart
@@ -31,27 +31,51 @@ void main() {
     });
 
     group('getVertexResponse', () {
-      test('returns a VertexResponse for api enabled', () async {
-        when(() => response.statusCode).thenReturn(200);
-        final vertexResponse = VertexResponse(
-          summary: '',
-          documents: const [
-            VertexDocument(
-              metadata: VertexMetadata(url: '', title: '', description: ''),
-            ),
-          ],
-        );
-        when(() => response.body).thenReturn(
-          jsonEncode(vertexResponse.toJson()),
-        );
-        final result = await questionsResourceApiEnabled.getVertexResponse('');
-        expect(result, equals(vertexResponse));
+      group('realApiEnabled=true', () {
+        test('returns a VertexResponse if success', () async {
+          when(() => response.statusCode).thenReturn(200);
+          final vertexResponse = VertexResponse(
+            summary: '',
+            documents: const [
+              VertexDocument(
+                metadata: VertexMetadata(url: '', title: '', description: ''),
+              ),
+            ],
+          );
+          when(() => response.body).thenReturn(
+            jsonEncode(vertexResponse.toJson()),
+          );
+          final result =
+              await questionsResourceApiEnabled.getVertexResponse('');
+          expect(result, equals(vertexResponse));
+        });
+
+        test('throws ApiClientError when request fails', () async {
+          when(() => response.statusCode).thenReturn(500);
+          when(() => response.body).thenReturn('Ops');
+          await expectLater(
+            questionsResourceApiEnabled.getVertexResponse(''),
+            throwsA(isA<ApiClientError>()),
+          );
+        });
+
+        test('throws ApiClientError when request success but wrong body',
+            () async {
+          when(() => response.statusCode).thenReturn(200);
+          when(() => response.body).thenReturn('Ops');
+          await expectLater(
+            questionsResourceApiEnabled.getVertexResponse(''),
+            throwsA(isA<ApiClientError>()),
+          );
+        });
       });
 
-      test('returns a VertexResponse for api disabled', () async {
-        final result =
-            await questionsResourceApiNotEnabled.getVertexResponse('');
-        expect(result, isA<VertexResponse>());
+      group('realApiEnabled=false', () {
+        test('returns a VertexResponse', () async {
+          final result =
+              await questionsResourceApiNotEnabled.getVertexResponse('');
+          expect(result, isA<VertexResponse>());
+        });
       });
     });
   });