snapshot/mac: MachOImageAnnotationsReader test shouldn’t crash with a nullptr ProcessReader::Module

snapshot/mac/mach_o_image_annotations_reader_test.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 80 matching lines @@
 
     ProcessReader process_reader;
     bool rv = process_reader.Initialize(task);
     if (!rv) {
       ADD_FAILURE();
     } else {
       const std::vector<ProcessReader::Module>& modules =
           process_reader.Modules();
       std::vector<std::string> all_annotations_vector;
       for (const ProcessReader::Module& module : modules) {
-        MachOImageAnnotationsReader module_annotations_reader(
-            &process_reader, module.reader, module.name);
-        std::vector<std::string> module_annotations_vector =
-            module_annotations_reader.Vector();
-        all_annotations_vector.insert(all_annotations_vector.end(),
-                                      module_annotations_vector.begin(),
-                                      module_annotations_vector.end());
+        if (module.reader) {
+          MachOImageAnnotationsReader module_annotations_reader(
+              &process_reader, module.reader, module.name);
+          std::vector<std::string> module_annotations_vector =
+              module_annotations_reader.Vector();
+          all_annotations_vector.insert(all_annotations_vector.end(),
+                                        module_annotations_vector.begin(),
+                                        module_annotations_vector.end());
+        } else {
+          EXPECT_TRUE(module.reader);
+        }
       }
 
       // Mac OS X 10.6 doesn’t have support for CrashReporter annotations
       // (CrashReporterClient.h), so don’t look for any special annotations in
       // that version.
       int mac_os_x_minor_version = MacOSXMinorVersion();
       if (mac_os_x_minor_version > 7) {
         EXPECT_GE(all_annotations_vector.size(), 1u);
 
         const char* expected_annotation = nullptr;
@@ skipping 212 matching lines @@
 
 TEST(MachOImageAnnotationsReader, CrashDyld) {
   TestMachOImageAnnotationsReader test_mach_o_image_annotations_reader(
       TestMachOImageAnnotationsReader::kCrashDyld);
   test_mach_o_image_annotations_reader.Run();
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace crashpad